Re: [time-nuts] PICTIC II parts from Mouser in da house!
All of the PICs I ordered came in on Friday (Mouser ships FAST!) so it's a matter of programming them and getting them out this week. Just an FYI guys, I'm leaving for southern Arizona for three weeks for work. If I don't get them out this week I will do my very best to get them out while I'm on base in AZ. -Bob On Sun, Jul 18, 2010 at 9:37 PM, Dick Moore rich...@hughes.net wrote: Got the package today from Mouser with everything there. Now to send the PIC chip to Bob Darlington for programming. And get the board from Stanley Reynolds. Best, Dick Moore ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] PICTIC II Parts from Mouser
Here we go again! The TS272ACN has just gone 'non-stocked' at Mouser. Will the TS272CN degrade the performance? It looks like the difference between the two is the TS272CN has a higher input offset voltage. Ed ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PICTIC II Parts from Mouser
The TS272CN is an acceptable substitute for the TS272ACN in the PICTIC II but as noted has a higher input offset voltage. This can be compensated for in the second stage by adjustment of the offset trimmer. I selected premium parts for temperature stability in the application. Sorry the manufacturers are making human compatible devices obsolete and only carrying over surface mount devices as they go Pb free for the EU market. Makes it difficult to keep up with what's available and harder for amateurs with fat fingers and poor eyesight like myself to build simple projects! Richard Here we go again! The TS272ACN has just gone 'non-stocked' at Mouser. Will the TS272CN degrade the performance? It looks like the difference between the two is the TS272CN has a higher input offset voltage. Ed ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] PICTIC II parts from Mouser in da house!
Got the package today from Mouser with everything there. Now to send the PIC chip to Bob Darlington for programming. And get the board from Stanley Reynolds. Best, Dick Moore ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PICTIC II Parts at Mouser
I see that the 74AC175 in the Mouser project has now morphed to a 75AC*T*175. Was that substitution intentional? I think it should be okay, just wanted to check. (What? Paranoid? Who said that?!) Ed Richard H McCorkle wrote: Time-Nuts, When the PICTIC was first developed a number of front-end designs were evaluated with the 74AC175 providing the best characteristics, size, and speed in a DIP format. When the PICTIC was released in 2008 the 74AC175PC was in full production, but by the time the PICTIC II with the diode interpolator was released in 2010 the 74AC175PC was in lifetime buy status and there were no other manufacturers supplying the device. On 6/01/2010 when I checked there were 1500 available at Mouser and 1500 at Digikey with 10K available at the factory for lifetime buy so I was hopeful the remaining stock would satisfy the needs for PICTIC II construction for a while. By 07/05/2010 all stock at the factory and USA distributors was exhausted. There are 3500 left at Arrow Germany according to the Fairchild site, but that doesn’t help us much here in the USA. The rapid depletion of the stock makes it clear the 74AC175PC was in use commercially and the decision to stop production not well thought out based on the high demand for the remaining stock. The SOIC-16 version 74AC175SC is still available and can be used but will require a little creative imagination to attach it to the existing board. To retain the characteristics of the original design the 74AC175PC can be replaced with the SOIC version or by using two 74AC74 packages although either of these options will require a different circuit board layout to do it right. The dual 74AC74 synchronizers will probably not operate up to the same maximum clock speeds as the 74AC175 design due to higher distributed capacitance in the clock lines to the four flip-flops, which is one of the reasons the 74AC175 was originally chosen. The diode interpolator uses a 10ma charge current that the logic needs to sink to ground, and has a 0.7-2.7v span across the sample cap and up to 3.4v at the anode of the current source shunt so the logic high must reach 4.1v to keep the shunt diode fully turned off at the high end of the charge cycle. The 74HC175 is slower and only sinks 5.8ma so it can’t be used unless the clock rate is below 30 MHz, the interpolator current is reduced to 5ma, and smaller value sample caps are used. The requirement for the 4.1v logic high to keep the diodes turned off precludes the use of 74S175 or 74F175 bipolar logic as they only guarantee a logic high of 2.5v. Due to the rapid depletion of the available stock the 74AC175PC is now unobtanium, so for a DIP package solution to simplify construction the 74AC74 option appears to be the best compromise. I have posted two revisions of the PICTIC II board on the WIKI, one for use with the SOIC and one that uses two 74AC74 packages to replace the 74AC175. If you have a 74AC175PC already the original version of the board may be preferred, as it has been tested to 80 MHz. I have not had a chance to test the new board designs yet using the SOIC or 74AC74 synchronizers, but the changes do not affect the code or other portions of the design so they should provide similar results to at least 50 MHz and will probably run faster than this. The rapid depletion in 74AC175PC stock was a surprise to me and I am sorry for any inconvenience using this device in the PICTIC II may have caused. If anyone on the list stocked up on 74AC175PC devices before they became unobtanium perhaps they would be willing to sell some to those that have ordered boards from Stanley. For future users one of the revised boards using the SOIC or dual 74AC74 synchronizers on the K04BB WIKI can be used instead to get around the problem. Richard Hi The 74F175 is in stock at Mouser. I'll let Rich decide if it's good enough. Bob Sent from my iPhone On Jul 9, 2010, at 5:16 PM, Stanley Reynolds stanley_reyno...@yahoo.com wrote: I was thinking of using a 74F175 not as fast uses more power but I have it. Stanley snip 7) The 74AC175 is un-obtanium in a PDIP package the project shows a 74ACT SOIC version, you'll have to kludge it on to the board Logic levels on the clock may impact accuracy (but probably won't). snip ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts
Re: [time-nuts] PICTIC II Parts at Mouser
Hi There's been a thread on the 175. It's both the wrong logic level and package. The good news is that you can buy it. The other parts are obsolete. Bob Sent from my iPhone On Jul 10, 2010, at 4:56 PM, Ed Palmer ed_pal...@sasktel.net wrote: I see that the 74AC175 in the Mouser project has now morphed to a 75AC*T*175. Was that substitution intentional? I think it should be okay, just wanted to check. (What? Paranoid? Who said that?!) Ed Richard H McCorkle wrote: Time-Nuts, When the PICTIC was first developed a number of front-end designs were evaluated with the 74AC175 providing the best characteristics, size, and speed in a DIP format. When the PICTIC was released in 2008 the 74AC175PC was in full production, but by the time the PICTIC II with the diode interpolator was released in 2010 the 74AC175PC was in lifetime buy status and there were no other manufacturers supplying the device. On 6/01/2010 when I checked there were 1500 available at Mouser and 1500 at Digikey with 10K available at the factory for lifetime buy so I was hopeful the remaining stock would satisfy the needs for PICTIC II construction for a while. By 07/05/2010 all stock at the factory and USA distributors was exhausted. There are 3500 left at Arrow Germany according to the Fairchild site, but that doesn’t help us much here in the USA. The rapid depletion of the stock makes it clear the 74AC175PC was in use commercially and the decision to stop production not well thought out based on the high demand for the remaining stock. The SOIC-16 version 74AC175SC is still available and can be used but will require a little creative imagination to attach it to the existing board. To retain the characteristics of the original design the 74AC175PC can be replaced with the SOIC version or by using two 74AC74 packages although either of these options will require a different circuit board layout to do it right. The dual 74AC74 synchronizers will probably not operate up to the same maximum clock speeds as the 74AC175 design due to higher distributed capacitance in the clock lines to the four flip-flops, which is one of the reasons the 74AC175 was originally chosen. The diode interpolator uses a 10ma charge current that the logic needs to sink to ground, and has a 0.7-2.7v span across the sample cap and up to 3.4v at the anode of the current source shunt so the logic high must reach 4.1v to keep the shunt diode fully turned off at the high end of the charge cycle. The 74HC175 is slower and only sinks 5.8ma so it can’t be used unless the clock rate is below 30 MHz, the interpolator current is reduced to 5ma, and smaller value sample caps are used. The requirement for the 4.1v logic high to keep the diodes turned off precludes the use of 74S175 or 74F175 bipolar logic as they only guarantee a logic high of 2.5v. Due to the rapid depletion of the available stock the 74AC175PC is now unobtanium, so for a DIP package solution to simplify construction the 74AC74 option appears to be the best compromise. I have posted two revisions of the PICTIC II board on the WIKI, one for use with the SOIC and one that uses two 74AC74 packages to replace the 74AC175. If you have a 74AC175PC already the original version of the board may be preferred, as it has been tested to 80 MHz. I have not had a chance to test the new board designs yet using the SOIC or 74AC74 synchronizers, but the changes do not affect the code or other portions of the design so they should provide similar results to at least 50 MHz and will probably run faster than this. The rapid depletion in 74AC175PC stock was a surprise to me and I am sorry for any inconvenience using this device in the PICTIC II may have caused. If anyone on the list stocked up on 74AC175PC devices before they became unobtanium perhaps they would be willing to sell some to those that have ordered boards from Stanley. For future users one of the revised boards using the SOIC or dual 74AC74 synchronizers on the K04BB WIKI can be used instead to get around the problem. Richard Hi The 74F175 is in stock at Mouser. I'll let Rich decide if it's good enough. Bob Sent from my iPhone On Jul 9, 2010, at 5:16 PM, Stanley Reynolds stanley_reyno...@yahoo.com wrote: I was thinking of using a 74F175 not as fast uses more power but I have it. Stanley snip 7) The 74AC175 is un-obtanium in a PDIP package the project shows a 74ACT SOIC version, you'll have to kludge it on to the board Logic levels on the clock may impact accuracy (but probably won't). snip ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
[time-nuts] PICTIC II Parts at Mouser
Hi Ok, I've set up a new project at Mouser for the PICTIC II parts. Assuming the magic works it's at: http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=8736DCEE10 You can also go to their EZ Buy page and enter code 8736DCEE10 to get to the project. There are a few special features on this one: 1) The duplicate parts for the RS-232 via transistor are eliminated. It's set up to use the MAX-232 2) Two (hopefully correct sized) 14 pin sockets are included for the PIC and the front end chip 3) Minor substitutions are made here and there to save a few pennies 4) The cheaper (and available) 3/8 trimmers are used 5) The caps for the integrators are at 1000 pf, if you want to go faster, you'll have to substitute the correct parts 6) The oscillator is a 10 MHz unit, same comment as the integrator caps 7) The 74AC175 is un-obtanium in a PDIP package the project shows a 74ACT SOIC version, you'll have to kludge it on to the board Logic levels on the clock may impact accuracy (but probably won't). The RS-232 comes out to a header. I have not included anything to get to a normal cable and connector. I intend to simply lop the end off of a cable I have and solder it to the pc boardt. Same issue with coax going to the inputs. If you need 0.025 post connectors to attach in a more elegant fashion, you will have to add them. Power required is +12 at well under an amp. Just about any wall wart in existence should be fine for power. I assume you have 12 volts available - no wall wart on project list. There's also no enclosure on the project list. As far as I can see all the parts are now there and it's in ok to buy condition. Total price is $29.95 (just had to get it under $30 ...). I would suggest taking a look in your junk box before ordering. A lot of these parts are pretty common stuff. Where possible I've included the parts designators in the project list. That should make deleting things fairly easy. I have absolutely no affiliation with Mouser and make no claims at all about their prices being as good or better than anybody else's. It might be a wise idea to check the list over - I've been known to make typos in the past Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PICTIC II Parts at Mouser
I was thinking of using a 74F175 not as fast uses more power but I have it. Stanley snip 7) The 74AC175 is un-obtanium in a PDIP package the project shows a 74ACT SOIC version, you'll have to kludge it on to the board Logic levels on the clock may impact accuracy (but probably won't). snip ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PICTIC II Parts at Mouser
Hi The 74F175 is in stock at Mouser. I'll let Rich decide if it's good enough. Bob Sent from my iPhone On Jul 9, 2010, at 5:16 PM, Stanley Reynolds stanley_reyno...@yahoo.com wrote: I was thinking of using a 74F175 not as fast uses more power but I have it. Stanley snip 7) The 74AC175 is un-obtanium in a PDIP package the project shows a 74ACT SOIC version, you'll have to kludge it on to the board Logic levels on the clock may impact accuracy (but probably won't). snip ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PICTIC II Parts at Mouser
Time-Nuts, When the PICTIC was first developed a number of front-end designs were evaluated with the 74AC175 providing the best characteristics, size, and speed in a DIP format. When the PICTIC was released in 2008 the 74AC175PC was in full production, but by the time the PICTIC II with the diode interpolator was released in 2010 the 74AC175PC was in lifetime buy status and there were no other manufacturers supplying the device. On 6/01/2010 when I checked there were 1500 available at Mouser and 1500 at Digikey with 10K available at the factory for lifetime buy so I was hopeful the remaining stock would satisfy the needs for PICTIC II construction for a while. By 07/05/2010 all stock at the factory and USA distributors was exhausted. There are 3500 left at Arrow Germany according to the Fairchild site, but that doesnt help us much here in the USA. The rapid depletion of the stock makes it clear the 74AC175PC was in use commercially and the decision to stop production not well thought out based on the high demand for the remaining stock. The SOIC-16 version 74AC175SC is still available and can be used but will require a little creative imagination to attach it to the existing board. To retain the characteristics of the original design the 74AC175PC can be replaced with the SOIC version or by using two 74AC74 packages although either of these options will require a different circuit board layout to do it right. The dual 74AC74 synchronizers will probably not operate up to the same maximum clock speeds as the 74AC175 design due to higher distributed capacitance in the clock lines to the four flip-flops, which is one of the reasons the 74AC175 was originally chosen. The diode interpolator uses a 10ma charge current that the logic needs to sink to ground, and has a 0.7-2.7v span across the sample cap and up to 3.4v at the anode of the current source shunt so the logic high must reach 4.1v to keep the shunt diode fully turned off at the high end of the charge cycle. The 74HC175 is slower and only sinks 5.8ma so it cant be used unless the clock rate is below 30 MHz, the interpolator current is reduced to 5ma, and smaller value sample caps are used. The requirement for the 4.1v logic high to keep the diodes turned off precludes the use of 74S175 or 74F175 bipolar logic as they only guarantee a logic high of 2.5v. Due to the rapid depletion of the available stock the 74AC175PC is now unobtanium, so for a DIP package solution to simplify construction the 74AC74 option appears to be the best compromise. I have posted two revisions of the PICTIC II board on the WIKI, one for use with the SOIC and one that uses two 74AC74 packages to replace the 74AC175. If you have a 74AC175PC already the original version of the board may be preferred, as it has been tested to 80 MHz. I have not had a chance to test the new board designs yet using the SOIC or 74AC74 synchronizers, but the changes do not affect the code or other portions of the design so they should provide similar results to at least 50 MHz and will probably run faster than this. The rapid depletion in 74AC175PC stock was a surprise to me and I am sorry for any inconvenience using this device in the PICTIC II may have caused. If anyone on the list stocked up on 74AC175PC devices before they became unobtanium perhaps they would be willing to sell some to those that have ordered boards from Stanley. For future users one of the revised boards using the SOIC or dual 74AC74 synchronizers on the K04BB WIKI can be used instead to get around the problem. Richard Hi The 74F175 is in stock at Mouser. I'll let Rich decide if it's good enough. Bob Sent from my iPhone On Jul 9, 2010, at 5:16 PM, Stanley Reynolds stanley_reyno...@yahoo.com wrote: I was thinking of using a 74F175 not as fast uses more power but I have it. Stanley snip 7) The 74AC175 is un-obtanium in a PDIP package the project shows a 74ACT SOIC version, you'll have to kludge it on to the board Logic levels on the clock may impact accuracy (but probably won't). snip ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PICTIC II Parts at Mouser
Richard, For the original circuit board, what about the 74AC175 SOIC soldered to an SOIC to DIP adapter? These adapters are available cheap on the auction site and there should be very little difference between this and the DIP version (the pinouts for both versions are the same). Would this compromise the higher frequency versions of the PICTIC II? Ed Richard H McCorkle wrote: Time-Nuts, When the PICTIC was first developed a number of front-end designs were evaluated with the 74AC175 providing the best characteristics, size, and speed in a DIP format. When the PICTIC was released in 2008 the 74AC175PC was in full production, but by the time the PICTIC II with the diode interpolator was released in 2010 the 74AC175PC was in lifetime buy status and there were no other manufacturers supplying the device. On 6/01/2010 when I checked there were 1500 available at Mouser and 1500 at Digikey with 10K available at the factory for lifetime buy so I was hopeful the remaining stock would satisfy the needs for PICTIC II construction for a while. By 07/05/2010 all stock at the factory and USA distributors was exhausted. There are 3500 left at Arrow Germany according to the Fairchild site, but that doesn’t help us much here in the USA. The rapid depletion of the stock makes it clear the 74AC175PC was in use commercially and the decision to stop production not well thought out based on the high demand for the remaining stock. The SOIC-16 version 74AC175SC is still available and can be used but will require a little creative imagination to attach it to the existing board. To retain the characteristics of the original design the 74AC175PC can be replaced with the SOIC version or by using two 74AC74 packages although either of these options will require a different circuit board layout to do it right. The dual 74AC74 synchronizers will probably not operate up to the same maximum clock speeds as the 74AC175 design due to higher distributed capacitance in the clock lines to the four flip-flops, which is one of the reasons the 74AC175 was originally chosen. The diode interpolator uses a 10ma charge current that the logic needs to sink to ground, and has a 0.7-2.7v span across the sample cap and up to 3.4v at the anode of the current source shunt so the logic high must reach 4.1v to keep the shunt diode fully turned off at the high end of the charge cycle. The 74HC175 is slower and only sinks 5.8ma so it can’t be used unless the clock rate is below 30 MHz, the interpolator current is reduced to 5ma, and smaller value sample caps are used. The requirement for the 4.1v logic high to keep the diodes turned off precludes the use of 74S175 or 74F175 bipolar logic as they only guarantee a logic high of 2.5v. Due to the rapid depletion of the available stock the 74AC175PC is now unobtanium, so for a DIP package solution to simplify construction the 74AC74 option appears to be the best compromise. I have posted two revisions of the PICTIC II board on the WIKI, one for use with the SOIC and one that uses two 74AC74 packages to replace the 74AC175. If you have a 74AC175PC already the original version of the board may be preferred, as it has been tested to 80 MHz. I have not had a chance to test the new board designs yet using the SOIC or 74AC74 synchronizers, but the changes do not affect the code or other portions of the design so they should provide similar results to at least 50 MHz and will probably run faster than this. The rapid depletion in 74AC175PC stock was a surprise to me and I am sorry for any inconvenience using this device in the PICTIC II may have caused. If anyone on the list stocked up on 74AC175PC devices before they became unobtanium perhaps they would be willing to sell some to those that have ordered boards from Stanley. For future users one of the revised boards using the SOIC or dual 74AC74 synchronizers on the K04BB WIKI can be used instead to get around the problem. Richard ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PICTIC II Parts at Mouser
Any chance that someone could purchase a small quantity from Arrow Germany so Stanley could include them with the boards we ordered? Extra payment for the chips, of course. Joe Gray W5JG On Fri, Jul 9, 2010 at 7:21 PM, Richard H McCorkle mccor...@ptialaska.net wrote: Time-Nuts, When the PICTIC was first developed a number of front-end designs were evaluated with the 74AC175 providing the best characteristics, size, and speed in a DIP format. When the PICTIC was released in 2008 the 74AC175PC was in full production, but by the time the PICTIC II with the diode interpolator was released in 2010 the 74AC175PC was in lifetime buy status and there were no other manufacturers supplying the device. On 6/01/2010 when I checked there were 1500 available at Mouser and 1500 at Digikey with 10K available at the factory for lifetime buy so I was hopeful the remaining stock would satisfy the needs for PICTIC II construction for a while. By 07/05/2010 all stock at the factory and USA distributors was exhausted. There are 3500 left at Arrow Germany according to the Fairchild site, but that doesn’t help us much here in the USA. The rapid depletion of the stock makes it clear the 74AC175PC was in use commercially and the decision to stop production not well thought out based on the high demand for the remaining stock. The SOIC-16 version 74AC175SC is still available and can be used but will require a little creative imagination to attach it to the existing board. To retain the characteristics of the original design the 74AC175PC can be replaced with the SOIC version or by using two 74AC74 packages although either of these options will require a different circuit board layout to do it right. The dual 74AC74 synchronizers will probably not operate up to the same maximum clock speeds as the 74AC175 design due to higher distributed capacitance in the clock lines to the four flip-flops, which is one of the reasons the 74AC175 was originally chosen. The diode interpolator uses a 10ma charge current that the logic needs to sink to ground, and has a 0.7-2.7v span across the sample cap and up to 3.4v at the anode of the current source shunt so the logic high must reach 4.1v to keep the shunt diode fully turned off at the high end of the charge cycle. The 74HC175 is slower and only sinks 5.8ma so it can’t be used unless the clock rate is below 30 MHz, the interpolator current is reduced to 5ma, and smaller value sample caps are used. The requirement for the 4.1v logic high to keep the diodes turned off precludes the use of 74S175 or 74F175 bipolar logic as they only guarantee a logic high of 2.5v. Due to the rapid depletion of the available stock the 74AC175PC is now unobtanium, so for a DIP package solution to simplify construction the 74AC74 option appears to be the best compromise. I have posted two revisions of the PICTIC II board on the WIKI, one for use with the SOIC and one that uses two 74AC74 packages to replace the 74AC175. If you have a 74AC175PC already the original version of the board may be preferred, as it has been tested to 80 MHz. I have not had a chance to test the new board designs yet using the SOIC or 74AC74 synchronizers, but the changes do not affect the code or other portions of the design so they should provide similar results to at least 50 MHz and will probably run faster than this. The rapid depletion in 74AC175PC stock was a surprise to me and I am sorry for any inconvenience using this device in the PICTIC II may have caused. If anyone on the list stocked up on 74AC175PC devices before they became unobtanium perhaps they would be willing to sell some to those that have ordered boards from Stanley. For future users one of the revised boards using the SOIC or dual 74AC74 synchronizers on the K04BB WIKI can be used instead to get around the problem. Richard Hi The 74F175 is in stock at Mouser. I'll let Rich decide if it's good enough. Bob Sent from my iPhone On Jul 9, 2010, at 5:16 PM, Stanley Reynolds stanley_reyno...@yahoo.com wrote: I was thinking of using a 74F175 not as fast uses more power but I have it. Stanley snip 7) The 74AC175 is un-obtanium in a PDIP package the project shows a 74ACT SOIC version, you'll have to kludge it on to the board Logic levels on the clock may impact accuracy (but probably won't). snip ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to
Re: [time-nuts] PICTIC II Parts at Mouser
Ed, This should work just as well as the original without compromizing the maximum clock rate. Richard Richard, For the original circuit board, what about the 74AC175 SOIC soldered to an SOIC to DIP adapter? These adapters are available cheap on the auction site and there should be very little difference between this and the DIP version (the pinouts for both versions are the same). Would this compromise the higher frequency versions of the PICTIC II? Ed Richard H McCorkle wrote: Time-Nuts, When the PICTIC was first developed a number of front-end designs were evaluated with the 74AC175 providing the best characteristics, size, and speed in a DIP format. When the PICTIC was released in 2008 the 74AC175PC was in full production, but by the time the PICTIC II with the diode interpolator was released in 2010 the 74AC175PC was in lifetime buy status and there were no other manufacturers supplying the device. On 6/01/2010 when I checked there were 1500 available at Mouser and 1500 at Digikey with 10K available at the factory for lifetime buy so I was hopeful the remaining stock would satisfy the needs for PICTIC II construction for a while. By 07/05/2010 all stock at the factory and USA distributors was exhausted. There are 3500 left at Arrow Germany according to the Fairchild site, but that doesnt help us much here in the USA. The rapid depletion of the stock makes it clear the 74AC175PC was in use commercially and the decision to stop production not well thought out based on the high demand for the remaining stock. The SOIC-16 version 74AC175SC is still available and can be used but will require a little creative imagination to attach it to the existing board. To retain the characteristics of the original design the 74AC175PC can be replaced with the SOIC version or by using two 74AC74 packages although either of these options will require a different circuit board layout to do it right. The dual 74AC74 synchronizers will probably not operate up to the same maximum clock speeds as the 74AC175 design due to higher distributed capacitance in the clock lines to the four flip-flops, which is one of the reasons the 74AC175 was originally chosen. The diode interpolator uses a 10ma charge current that the logic needs to sink to ground, and has a 0.7-2.7v span across the sample cap and up to 3.4v at the anode of the current source shunt so the logic high must reach 4.1v to keep the shunt diode fully turned off at the high end of the charge cycle. The 74HC175 is slower and only sinks 5.8ma so it cant be used unless the clock rate is below 30 MHz, the interpolator current is reduced to 5ma, and smaller value sample caps are used. The requirement for the 4.1v logic high to keep the diodes turned off precludes the use of 74S175 or 74F175 bipolar logic as they only guarantee a logic high of 2.5v. Due to the rapid depletion of the available stock the 74AC175PC is now unobtanium, so for a DIP package solution to simplify construction the 74AC74 option appears to be the best compromise. I have posted two revisions of the PICTIC II board on the WIKI, one for use with the SOIC and one that uses two 74AC74 packages to replace the 74AC175. If you have a 74AC175PC already the original version of the board may be preferred, as it has been tested to 80 MHz. I have not had a chance to test the new board designs yet using the SOIC or 74AC74 synchronizers, but the changes do not affect the code or other portions of the design so they should provide similar results to at least 50 MHz and will probably run faster than this. The rapid depletion in 74AC175PC stock was a surprise to me and I am sorry for any inconvenience using this device in the PICTIC II may have caused. If anyone on the list stocked up on 74AC175PC devices before they became unobtanium perhaps they would be willing to sell some to those that have ordered boards from Stanley. For future users one of the revised boards using the SOIC or dual 74AC74 synchronizers on the K04BB WIKI can be used instead to get around the problem. Richard ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PICTIC II Parts at Mouser
Hi For around $4 or so you can get a CPLD and socket that will replace all of the logic chips. They will run on +5 and go to 100 MHz. My guess is that they would be a bit more repeatable. The downside is it's another part to program. Bob Sent from my iPhone On Jul 9, 2010, at 10:02 PM, Richard H McCorkle mccor...@ptialaska.net wrote: Ed, This should work just as well as the original without compromizing the maximum clock rate. Richard Richard, For the original circuit board, what about the 74AC175 SOIC soldered to an SOIC to DIP adapter? These adapters are available cheap on the auction site and there should be very little difference between this and the DIP version (the pinouts for both versions are the same). Would this compromise the higher frequency versions of the PICTIC II? Ed Richard H McCorkle wrote: Time-Nuts, When the PICTIC was first developed a number of front-end designs were evaluated with the 74AC175 providing the best characteristics, size, and speed in a DIP format. When the PICTIC was released in 2008 the 74AC175PC was in full production, but by the time the PICTIC II with the diode interpolator was released in 2010 the 74AC175PC was in lifetime buy status and there were no other manufacturers supplying the device. On 6/01/2010 when I checked there were 1500 available at Mouser and 1500 at Digikey with 10K available at the factory for lifetime buy so I was hopeful the remaining stock would satisfy the needs for PICTIC II construction for a while. By 07/05/2010 all stock at the factory and USA distributors was exhausted. There are 3500 left at Arrow Germany according to the Fairchild site, but that doesn’t help us much here in the USA. The rapid depletion of the stock makes it clear the 74AC175PC was in use commercially and the decision to stop production not well thought out based on the high demand for the remaining stock. The SOIC-16 version 74AC175SC is still available and can be used but will require a little creative imagination to attach it to the existing board. To retain the characteristics of the original design the 74AC175PC can be replaced with the SOIC version or by using two 74AC74 packages although either of these options will require a different circuit board layout to do it right. The dual 74AC74 synchronizers will probably not operate up to the same maximum clock speeds as the 74AC175 design due to higher distributed capacitance in the clock lines to the four flip-flops, which is one of the reasons the 74AC175 was originally chosen. The diode interpolator uses a 10ma charge current that the logic needs to sink to ground, and has a 0.7-2.7v span across the sample cap and up to 3.4v at the anode of the current source shunt so the logic high must reach 4.1v to keep the shunt diode fully turned off at the high end of the charge cycle. The 74HC175 is slower and only sinks 5.8ma so it can’t be used unless the clock rate is below 30 MHz, the interpolator current is reduced to 5ma, and smaller value sample caps are used. The requirement for the 4.1v logic high to keep the diodes turned off precludes the use of 74S175 or 74F175 bipolar logic as they only guarantee a logic high of 2.5v. Due to the rapid depletion of the available stock the 74AC175PC is now unobtanium, so for a DIP package solution to simplify construction the 74AC74 option appears to be the best compromise. I have posted two revisions of the PICTIC II board on the WIKI, one for use with the SOIC and one that uses two 74AC74 packages to replace the 74AC175. If you have a 74AC175PC already the original version of the board may be preferred, as it has been tested to 80 MHz. I have not had a chance to test the new board designs yet using the SOIC or 74AC74 synchronizers, but the changes do not affect the code or other portions of the design so they should provide similar results to at least 50 MHz and will probably run faster than this. The rapid depletion in 74AC175PC stock was a surprise to me and I am sorry for any inconvenience using this device in the PICTIC II may have caused. If anyone on the list stocked up on 74AC175PC devices before they became unobtanium perhaps they would be willing to sell some to those that have ordered boards from Stanley. For future users one of the revised boards using the SOIC or dual 74AC74 synchronizers on the K04BB WIKI can be used instead to get around the problem. Richard ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list --
