[Repeater-Builder] Re: Anyone got a Amp-meter Circuit to Repeater Controller for Telementry Readback?
Kevin, Here is what I use. A 100 Amp shunt with big wire connections to go in series with the battery leads, and small set of screw terminals to connect to the sensing circuit. The one below generates 100 MV of voltage at 100 amps of battery charge. http://store.solar-electric.com/mka-100-100.html For a circuit we use the one that Ken has provided on page 13 in his Arcom RC-210 manual, since we mainly use RC-210 controllers, but the same circuit will work with any controller. All we are doing is using a OP-Amp for a voltage multiplier. Then you adjust your meter face accordingly in the controller configuration. http://www.arcomcontrollers.com/ftp/pub/manuals/rc2103_0ahardware.pdf To calculate the values for the resistors in the op amp circuit so that I can get the desired voltage change where 100 mv full output from the shunt equals about 4 volts, I use this handy little tool. http://www.daycounter.com/Calculators/Op-Amp/Op-Amp-Voltage-Calculator.phtml We sometimes will do two of these charging indication circuits, so that we can monitor solar and wind charge rates independently. Hope this helps. Joe - WA7JAW --- In Repeater-Builder@yahoogroups.com, Gmail - Kevin, Natalia, Stacey Rochelle spar...@... wrote: Hi All, I am in need of a circuit to read amps to my controller. Want to be able to read the current being used at the repeater site as well as the charging current to the batteries. I am using a RLC-3 controller. I have a current meter in-line at the site, but a reference from the repeater would be a great help. Thanks Kevin, ZL1KFM.
[Repeater-Builder] Re: Anyone got a Amp-meter Circuit to Repeater Controller for Telementry Readback?
Kevin, are you using a charge controller between the solar panel, rpt, and batteries? Does your controller provide any kind of monitoring of current or voltage or state of charge? The op-amp circuits can also be extended in range beyond the VCC by using a voltage divider on each side of the input voltage. 1k 1% resistors are my fave for this divider type of app. Keeps the impedance low enough you can get good gain on the op amp with reasonable component values. You might want to consider some sort of outboard microcontroller based data logger. It could tell you how many charge hours you are getting, and peak amps, total amps, and at what time of day your batteries reach full charge and when the charge controller begins to dump excess voltage. This can let you know your batteries are doing through the days / nights. I built an APRS digipeater some years back that ran solar. Low power short burst tx, It would fail in late December due to lack of sunlight, and be fine otherwise throughout the year. Enjoy tinkering! Ed N3SDO http://geo.yahoo.com/serv?s=97359714/grpId=104168/grpspId=1705063108/ms gId=90412/stime=1238701456/nc1=5349272/nc2=4836040/nc3=5191955
Re: [Repeater-Builder] Re: Anyone got a Amp-meter Circuit to Repeater Controller for Telementry Readback?
Ed and Others Thanks for your ideas and thoughts. The solar cells have a small regulator in line to the batteries, then batteries to repeater system. We do have mains to the site but this is only for requirements when there is heavy usage and the voltage gets down. The controller will switch to the mains. I have everything else working okay, I was just having problems getting a read-out for AMPS. I like your other ideas and will look at these, when I have some free time to research, many projects on the go. Wife wants this done, I want to get my shack closer to finished, want to put my 9mtr poles up for my Hoz 80mtr loop, and plenty of jobs around the new house and section. I will be employed for the next 2-3 life-times :) Regards Kevin, ZL1KFM. - Original Message - From: Ed Bathgate To: Repeater-Builder@yahoogroups.com Sent: Saturday, April 04, 2009 6:56 AM Subject: [Repeater-Builder] Re: Anyone got a Amp-meter Circuit to Repeater Controller for Telementry Readback? Kevin, are you using a charge controller between the solar panel, rpt, and batteries? Does your controller provide any kind of monitoring of current or voltage or state of charge? The op-amp circuits can also be extended in range beyond the VCC by using a voltage divider on each side of the input voltage. 1k 1% resistors are my fave for this divider type of app. Keeps the impedance low enough you can get good gain on the op amp with reasonable component values. You might want to consider some sort of outboard microcontroller based data logger. It could tell you how many charge hours you are getting, and peak amps, total amps, and at what time of day your batteries reach full charge and when the charge controller begins to dump excess voltage. This can let you know your batteries are doing through the days / nights. I built an APRS digipeater some years back that ran solar. Low power short burst tx, It would fail in late December due to lack of sunlight, and be fine otherwise throughout the year. Enjoy tinkering! Ed N3SDO
[Repeater-Builder] Re: Anyone got a Amp-meter Circuit to Repeater Controller for Telementry Readback?
--- In Repeater-Builder@yahoogroups.com, Gmail - Kevin, Natalia, Stacey Rochelle spar...@... wrote: Hi All, I am in need of a circuit to read amps to my controller. Want to be able to read the current being used at the repeater site as well as the charging current to the batteries. Kevin, Is your rack on a single phase feed? If so, placing a current transformer in the black lead will give you a output current proportional to to the input. Put a resistor across it and use the voltage input to the controller. The downside to this approach is the controller will talk the current and label it volts. Martin
Re: [Repeater-Builder] Re: Anyone got a Amp-meter Circuit to Repeater Controller for Telementry Readback?
Hi Martin, This is a 13.8v system, run off batteries and solar cells, the reason to be able to monitor current, charging the batteries and current drain from the repeater system. I can monitor volts ok, just those damm amps running around. Kevin, ZL1KFM. - Original Message - From: rahwayflynn To: Repeater-Builder@yahoogroups.com Sent: Friday, April 03, 2009 12:31 AM Subject: [Repeater-Builder] Re: Anyone got a Amp-meter Circuit to Repeater Controller for Telementry Readback? --- In Repeater-Builder@yahoogroups.com, Gmail - Kevin, Natalia, Stacey Rochelle spar...@... wrote: Hi All, I am in need of a circuit to read amps to my controller. Want to be able to read the current being used at the repeater site as well as the charging current to the batteries. Kevin, Is your rack on a single phase feed? If so, placing a current transformer in the black lead will give you a output current proportional to to the input. Put a resistor across it and use the voltage input to the controller. The downside to this approach is the controller will talk the current and label it volts. Martin
Re: [Repeater-Builder] Re: Anyone got a Amp-meter Circuit to Repeater Controller for Telementry Readback?
Even for a on site solution, I'd love to get some suggestions as to how the rest of the RB community measures current draw on their repeater systems for the sake of battery backup time/size calculations, proper powering, etc 2009/4/2 Gmail - Kevin, Natalia, Stacey Rochelle spar...@gmail.com Hi Martin, This is a 13.8v system, run off batteries and solar cells, the reason to be able to monitor current, charging the batteries and current drain from the repeater system. I can monitor volts ok, just those damm amps running around. Kevin, ZL1KFM. - Original Message - *From:* rahwayflynn mafl...@att.net *To:* Repeater-Builder@yahoogroups.com *Sent:* Friday, April 03, 2009 12:31 AM *Subject:* [Repeater-Builder] Re: Anyone got a Amp-meter Circuit to Repeater Controller for Telementry Readback? --- In Repeater-Builder@yahoogroups.com, Gmail - Kevin, Natalia, Stacey Rochelle spar...@... wrote: Hi All, I am in need of a circuit to read amps to my controller. Want to be able to read the current being used at the repeater site as well as the charging current to the batteries. Kevin, Is your rack on a single phase feed? If so, placing a current transformer in the black lead will give you a output current proportional to to the input. Put a resistor across it and use the voltage input to the controller. The downside to this approach is the controller will talk the current and label it volts. Martin
RE: [Repeater-Builder] Re: Anyone got a Amp-meter Circuit to Repeater Controller for Telementry Readback?
The classic textbook method would be to put a current shunt in series with your DC source and measure the voltage drop across it. A current shunt is just a precision low-value resistor capable of handling the thru-current, nothing fancy about it. But, at low voltages (like 12V) and low currents (like a few tens of amps), you end up with small voltages across the shunt in the practical world. The resistance of the shunt has to be kept very low, like in the hundreths or thousandths of an ohm, to minimize power loss through the shunt. A 0.001 ohm shunt would only give you 50 mV with 50A through it. Going to 0.01 ohms would give you 500 mV across the shunt at 50A, but obviously you've also dropped the voltage going to the equipment by 500 mV, and since you're running on solar/batteries, losing half a volt under load probably isn't ideal. So, keeping the R low and using DC amplification will probably be necessary when using a traditional current shunt in an installation like this to get any useful resolution out of your controller's A/D converter. A more-modern approach would be to use a Hall effect current sensor. Hall effect sensors come in various flavors, anything from a bare-bones IC that you can use to build your own, or as ready-to-go packaged modules that you your DC+ conductor through, supply it with DC power, and it gives you a sample voltage output (typically 0-5V) proportional to the current through the sensor. Do some web searches and you should find all kinds of info. CR Magnetics comes to mind for off-the-shelf units. --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Gmail - Kevin, Natalia, Stacey Rochelle Sent: Thursday, April 02, 2009 3:43 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: Anyone got a Amp-meter Circuit to Repeater Controller for Telementry Readback? Hi Martin, This is a 13.8v system, run off batteries and solar cells, the reason to be able to monitor current, charging the batteries and current drain from the repeater system. I can monitor volts ok, just those damm amps running around. Kevin, ZL1KFM. - Original Message - From: rahwayflynn mailto:mafl...@att.net To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder@yahoogroups.com Sent: Friday, April 03, 2009 12:31 AM Subject: [Repeater-Builder] Re: Anyone got a Amp-meter Circuit to Repeater Controller for Telementry Readback? --- In Repeater-Builder@yahoogroups.com mailto:Repeater-Builder@yahoogroups.com , Gmail - Kevin, Natalia, Stacey Rochelle spar...@... wrote: Hi All, I am in need of a circuit to read amps to my controller. Want to be able to read the current being used at the repeater site as well as the charging current to the batteries. Kevin, Is your rack on a single phase feed? If so, placing a current transformer in the black lead will give you a output current proportional to to the input. Put a resistor across it and use the voltage input to the controller. The downside to this approach is the controller will talk the current and label it volts. Martin No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.0.238 / Virus Database: 270.11.3/1970 - Release Date: 04/02/09 06:09:00
Re: [Repeater-Builder] Re: Anyone got a Amp-meter Circuit to Repeater Controller for Telementry Readback?
- Original Message - From: Jeff DePolo To: Repeater-Builder@yahoogroups.com Sent: Thursday, April 02, 2009 2:20 PM Subject: RE: [Repeater-Builder] Re: Anyone got a Amp-meter Circuit to Repeater Controller for Telementry Readback? The classic textbook method would be to put a current shunt in series with your DC source and measure the voltage drop across it. A current shunt is just a precision low-value resistor capable of handling the thru-current, nothing fancy about it. But, at low voltages (like 12V) and low currents (like a few tens of amps), you end up with small voltages across the shunt in the practical world. The resistance of the shunt has to be kept very low, like in the hundreths or thousandths of an ohm, to minimize power loss through the shunt. A 0.001 ohm shunt would only give you 50 mV with 50A through it. Going to 0.01 ohms would give you 500 mV across the shunt at 50A, but obviously you've also dropped the voltage going to the equipment by 500 mV, and since you're running on solar/batteries, losing half a volt under load probably isn't ideal. So, keeping the R low and using DC amplification will probably be necessary when using a traditional current shunt in an installation like this to get any useful resolution out of your controller's A/D converter. A more-modern approach would be to use a Hall effect current sensor. Hall effect sensors come in various flavors, anything from a bare-bones IC that you can use to build your own, or as ready-to-go packaged modules that you your DC+ conductor through, supply it with DC power, and it gives you a sample voltage output (typically 0-5V) proportional to the current through the sensor. Do some web searches and you should find all kinds of info. CR Magnetics comes to mind for off-the-shelf units. --- Jeff WN3A -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Gmail - Kevin, Natalia, Stacey Rochelle Sent: Thursday, April 02, 2009 3:43 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: Anyone got a Amp-meter Circuit to Repeater Controller for Telementry Readback? Hi Martin, This is a 13.8v system, run off batteries and solar cells, the reason to be able to monitor current, charging the batteries and current drain from the repeater system. I can monitor volts ok, just those damm amps running around. Kevin, ZL1KFM. - Original Message - From: rahwayflynn mailto:mafl...@att.net To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder@yahoogroups.com Sent: Friday, April 03, 2009 12:31 AM Subject: [Repeater-Builder] Re: Anyone got a Amp-meter Circuit to Repeater Controller for Telementry Readback? --- In Repeater-Builder@yahoogroups.com mailto:Repeater-Builder@yahoogroups.com , Gmail - Kevin, Natalia, Stacey Rochelle spar...@... wrote: Hi All, I am in need of a circuit to read amps to my controller. Want to be able to read the current being used at the repeater site as well as the charging current to the batteries. Kevin, Is your rack on a single phase feed? If so, placing a current transformer in the black lead will give you a output current proportional to to the input. Put a resistor across it and use the voltage input to the controller. The downside to this approach is the controller will talk the current and label it volts. Martin No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.0.238 / Virus Database: 270.11.3/1970 - Release Date: 04/02/09 06:09:00
Re: [Repeater-Builder] Re: Anyone got a Amp-meter Circuit to Repeater Controller for Telementry Readback?
Perhaps it's possible to detect the voltage drop on the existing [+] line from the battery bank, without the need for an additional shunt. Some precision, high-current power supplies use a separate pair of sense leads between the load and the voltage regulator, so the rated voltage appears at the load, compensating for the slight drop on the main power leads which occurs when high current is drawn. There's certainly not enough voltage drop on the line from Kevin's battery bank to the repeater to measure directly with the RLC-3's 0-5V analog input, but perhaps a well-built linear op-amp circuit could produce a useable 0-5V swing based on the much smaller voltage variation on the main power lead. Thoughts? 73, Paul, AE4KR - Original Message - From: Jeff DePolo To: Repeater-Builder@yahoogroups.com Sent: Thursday, April 02, 2009 2:20 PM Subject: RE: [Repeater-Builder] Re: Anyone got a Amp-meter Circuit to Repeater Controller for Telementry Readback? The classic textbook method would be to put a current shunt in series with your DC source and measure the voltage drop across it. A current shunt is just a precision low-value resistor capable of handling the thru-current, nothing fancy about it. But, at low voltages (like 12V) and low currents (like a few tens of amps), you end up with small voltages across the shunt in the practical world. The resistance of the shunt has to be kept very low, like in the hundreths or thousandths of an ohm, to minimize power loss through the shunt...
