On Monday 27 May 2013 09:08:30 Steve Stallings did opine: > > I did some trace cutting and made the output stage a gain of > > 1.45 or so, so > > I am now getting about 10.4 volts, which helped some. Now it > > looks as if I > > may be forced to trade the 7812 in my home made supply in for > > a 7815 or an > > LM317?, whatever the adjustable one is. > > Gene, > > You could always trick your 7812 into being an adjustable > regulator by attaching its ground leg to a resistor divider > off of the output. See Figure 4 at the bottom of page 8 in > this data sheet: > > http://www.ti.com/lit/ds/symlink/ua7805.pdf > > Regards, > Steve Stallings
Unforch, aware that it was going to get hot, and that it needed to float, I grabbed a 1.25x2.25 piece of double sided pcb, gooped that to a handy bit of angle alu for mounting after filing the copper back from the hot edges of floating side, and putting a good sized tip in my station, simply soldered the mounting tab to the pcb. Then used the copper foil on that side for a handy negative rail. And yes, with a 39 volt input from a 25.2 transformer feeding a bridge and 4700 uf cap, it did get hot, about 165F according to my IR thermometer. So I cabbaged a small power transformer out of a TRS-80 Coco computer and used its primary for a choke, converting the thing to a choke input filter that reduced the voltage from 39 to 22.5, still enough to run some 24 volt ice cube P&B relays to switch the motor around. IOW, the ground tab is not available to float. I also have an LM317T in case I have to get uber fancy, but the 7815 should do an adequate job, I just need to locate one. The shacks stock selection however is getting poorer & poorer, and they are getting tired of my telling them they have a great location to open a Radio Shack store. :) Arturo has finally realized that the so-called reversing relay lashup he has on the C41 is worthless because it cannot be controlled independently, instead dropping out a few milliseconds after the PWM stops. That will destroy motor controllers and may damage the PM field magnets when the controller suddenly sees a motor it thought was turning 7 grand in reverse, suddenly being put in the fwd mode with no time to brake it, and the analog from the PWM has not decayed to zero yet. I think your 106 also does this as I put a dropout delay in the .hal file for my mill, and that did not stop the controller from thumping the motor pretty hard when I issue an M5 to stop the tool from about 250 rpm in reverse, which I use, along with a G38.2 command to find the edge of something. The slowly turning bit makes a good contact (I have a .2 uf cap across the probe so it "stores" the momentary contact without touching the work hard enough to mark it) So the next run of C41's he makes will do the reverse as long as commanded from its input. FWIW, that is not a problem with the 106 when running it from the hand switches, then it works correctly, but then my dynamic braking there is resistive. With that much larger rotating mass in the lathe, I had hoped to be able to do a constant current active brake even if I had to put a full wave bridge on its input. The transistors I ordered turned out to not be up to the expected level of voltage for SOA though, so those are still laying in the shipping box. So I'll need to go hit the old transmitter site & see if I can source some old power R's, another of those 200 watt 5 ohm'ers to make 10 ohms should be about right. They'll never get hot of course. A 12.5 ohm 100 watter would be pure serendipity. But I don't recall one of those being in it from my nearly 20 years of keeping that old beast working. But today I promised to attack the jungle this place is turning into, and because a ramp & table I made to lift stuff up to stand-up height to work on it cuts the back yard in two, the upper half will have to be scalped with the weed eater. My tiller is still on the table as I've not been able to break the rust loose between the OEM axle and my axle extensions I put on it to widen the tread & prevent it from falling over. Its been soaked with PBblaster for weeks now. That has to come off before I can split the gear case & redesign a better shift lock, its stuck in gear. VERY common problem with that model according to my google fu. Thanks Steve. Cheers, Gene -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) My web page: <http://coyoteden.dyndns-free.com:85/gene> is up! My views <http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml> It's more than magnificent-it's mediocre. -Samuel Goldwyn A pen in the hand of this president is far more dangerous than 200 million guns in the hands of law-abiding citizens. ------------------------------------------------------------------------------ Try New Relic Now & We'll Send You this Cool Shirt New Relic is the only SaaS-based application performance monitoring service that delivers powerful full stack analytics. Optimize and monitor your browser, app, & servers with just a few lines of code. Try New Relic and get this awesome Nerd Life shirt! http://p.sf.net/sfu/newrelic_d2d_may _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
