does anyone have schematics for one....any idea how you could control both the voltage and current...help would be greatly appreciated...also its gotta be dual polarity........hey what about signal generaors...anyone out there built one?
oh and of course would the cost compared to usability warrant going DIY on this...or should i just cough up the cash for a used one....hmmm?
oh and of course would the cost compared to usability warrant going DIY on this...or should i just cough up the cash for a used one....hmmm?
if you look at the datasheet for the LM317 on National Semi's website you will find a schematic for a "dual-tracking" regulator -- you follow the tracking voltage regulator with an another LM317 set up as a current limiter -- for the negative voltage use the LM337 devices.
I just bought a bunch of Lambda 422FM supplies for the lab for less than $50 each -- these are dual 0 - 40V with adjustable voltage and current, meters for voltage and current. there is no way that you can beat this price -- even with shipping from the US to Europe. I also bought some Tektronix PS503A's for the undergrad lab -- these run about $35 each and can track if so desired. They fit into the TM5XX series of mainframes which are also very inexpensive.
I just bought a bunch of Lambda 422FM supplies for the lab for less than $50 each -- these are dual 0 - 40V with adjustable voltage and current, meters for voltage and current. there is no way that you can beat this price -- even with shipping from the US to Europe. I also bought some Tektronix PS503A's for the undergrad lab -- these run about $35 each and can track if so desired. They fit into the TM5XX series of mainframes which are also very inexpensive.
http://wwwd.national.com/national/PowerMB.nsf/0/37fc4547f388a0fc88256ccb00212e54?OpenDocument
if you use a dual pot it will track
i've considered "tricking" the part -- but you really do want both error amps minding their own business.
you can get down to "zero" volts by bringing the "adjust" pin down below the reference voltage of 1.25 V -- in a lab supply it's helpful to be able to get close to zero.
if you use a dual pot it will track
i've considered "tricking" the part -- but you really do want both error amps minding their own business.
you can get down to "zero" volts by bringing the "adjust" pin down below the reference voltage of 1.25 V -- in a lab supply it's helpful to be able to get close to zero.
need something ..yeah plus minus 40V would be good...i could say 5 amps...but thats really overkill....i will check up those ics thanks for the feedback guys.....
hey i got a question...when testing a large system of opamps transistors and the likes....should i just set the required voltage and then let the opams etc pull down the amount of current needed...or should i be able to control both voltage and current.....cause i remember those cool PSU at school where you could set both the voltage and the amperes...but im thinkin if u set the voltage to the required Vcc and Vee then u set a current...will that current be forced through the components at all time...or is that the maximum current available...forcing the current through sounds like a good contender for overheating devices.......please help feeling a bir confused....
hey i got a question...when testing a large system of opamps transistors and the likes....should i just set the required voltage and then let the opams etc pull down the amount of current needed...or should i be able to control both voltage and current.....cause i remember those cool PSU at school where you could set both the voltage and the amperes...but im thinkin if u set the voltage to the required Vcc and Vee then u set a current...will that current be forced through the components at all time...or is that the maximum current available...forcing the current through sounds like a good contender for overheating devices.......please help feeling a bir confused....
alecwek said:
If it's 5 amps you're looking for, then you are in an entirely different class of power supply --
for testing operational amplifiers rarely will you need more than a few hundred milliamps --
for matching transistors you will need an supply capable of around 1.5 amps -- for this purpose a Lambda 15 volt supply would be fine.
Hm, I need to make myself a bench supply one of these days. So, I'm wondering about the same as alecwek is.
If you use 2 LM317s, one to set the voltage and the second to set the current, what will happen? For example, let's say you set it to 12V 1A. Will the thing then continously give out 1A or will it cap the max output at 1A? (The latter seems more logical, since I don't really see how a supply could "force" more current though some resistors for example.)
If you use 2 LM317s, one to set the voltage and the second to set the current, what will happen? For example, let's say you set it to 12V 1A. Will the thing then continously give out 1A or will it cap the max output at 1A? (The latter seems more logical, since I don't really see how a supply could "force" more current though some resistors for example.)
You can use some LM317s in parallel, but instead of using a low value resistor on the output, use a diode. Then you know for sure they won't interfere with each other, but of course then you have to take in account the voltage drop over the diode.
But it's easy, you can stack like 100 of them in parallel and have a 150A power supply
(don't forget to add a lot of heatsinks to that ).
But it's easy, you can stack like 100 of them in parallel and have a 150A power supply
(don't forget to add a lot of heatsinks to that ).thanks........
these things are cool....one of the shematics(i have attached with this post...) which is on the data sheets...shows what it calls a constant current\voltage source but there are two variable resistors...one for setting of voltage the other for current...can i just strap on a current and voltage meter and use this as a ...(reliable) benchtop power supply.....gotts find myself a few of these to try them out....what anout negative voltage suplies...can i just hook it up backwards and use it to sink voltage and current (instead of sourcing it) then that will be my dual supply???
thanks for the many posts....
these things are cool....one of the shematics(i have attached with this post...) which is on the data sheets...shows what it calls a constant current\voltage source but there are two variable resistors...one for setting of voltage the other for current...can i just strap on a current and voltage meter and use this as a ...(reliable) benchtop power supply.....gotts find myself a few of these to try them out....what anout negative voltage suplies...can i just hook it up backwards and use it to sink voltage and current (instead of sourcing it) then that will be my dual supply???
thanks for the many posts....
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