I need to build a good bench psu for testing and troubleshooting solid state amplifiers. Any suggestions for one that will last through my growing knowledge base and technical ability.
Cheers
Cheers
A person's budget and power requirements come into play.
Very low noise and/or high power affects cost. Personally I'd stay away from used bench supplies. They are more often than not beat to death and out of caliberation.
Some of the Chinese bench supplies are pretty reasonable for price and perfirmance like Mastech. Agilent is more expensive, but very high quality.
Perhaps you could share your power requirements so we could provide better help.
Be VERY careful buying used power supplies on ebay. Pay more for a vendor who tests the units and warranties them.
-David
Very low noise and/or high power affects cost. Personally I'd stay away from used bench supplies. They are more often than not beat to death and out of caliberation.
Some of the Chinese bench supplies are pretty reasonable for price and perfirmance like Mastech. Agilent is more expensive, but very high quality.
Perhaps you could share your power requirements so we could provide better help.
Be VERY careful buying used power supplies on ebay. Pay more for a vendor who tests the units and warranties them.
-David
Audio testbench power supply
Have you perhaps studied the current limiting supply from Randy Slone? (chapter 13 diagnostic equipment) in his book titled 'High-Power Audio Amplification Construction Manual)
I myself wouldn't mind making one of these for my bench
Regards
Chris
Have you perhaps studied the current limiting supply from Randy Slone? (chapter 13 diagnostic equipment) in his book titled 'High-Power Audio Amplification Construction Manual)
I myself wouldn't mind making one of these for my bench
Regards
Chris
I have been toying with a DIY bench supply idea also.... started as a regulator for a class A amp... turned out it would be impractical for such a use, but it would make a beefy backbone for a bench PSU (0.6C/W heatsink) It still needs some tweaking as the voltage range is still slightly limited. slap on some needle type V and A meters and a PIC or pot to adjust voltage and Bob's your uncle. It won't have a current limiter but it is sure to outlive at least a 200W drawing.
Gavinator68 said:
hi.
I have built my own custom bench supply, from old reused transistors/components.
As I am more into pre amplifiers, than into power amplifiers
this one has not several Ampere output.
==========
Ouputs:
2 x 20 VDC ( +- 20 Volt = max 40 Volt )
.. adjustable From 2 x 0.00 V >to> 2 x 20.00 Volt
and some fixed voltages outputs:
+ 5.0 Volt
+ 8.0 Volt
- 8.0 Volt
The Max Current output for any of those is:
200 mA .. as I used only one smaller TRAFO = 15 VA
==========
I have published my Bench Supply in Power Supply Design forum.
Along with schematics.
Regards 🙂
Lineup
Lineup Audio power supply forum
Hi
try to find a secondhand version.
I suggest a two channel with output meters (analogue or digital) for both voltage and current.
The voltage should be adjustable from 0V to 30Vdc or more if that is your requirement.
Both channels should have an adjustable current limit, 0mA to 2000mA or even as high as 5000mA.
Better if both channels can be used and adjusted independently and very convenient if a push button is available to series connect the outputs for a dual polarity tracking supply.
This will serve for 95% of your lab power needs. If it has a 5A 5V aux supply even better.
Any specialised low noise or HF supplies can be built up specifically for the project.
try to find a secondhand version.
I suggest a two channel with output meters (analogue or digital) for both voltage and current.
The voltage should be adjustable from 0V to 30Vdc or more if that is your requirement.
Both channels should have an adjustable current limit, 0mA to 2000mA or even as high as 5000mA.
Better if both channels can be used and adjusted independently and very convenient if a push button is available to series connect the outputs for a dual polarity tracking supply.
This will serve for 95% of your lab power needs. If it has a 5A 5V aux supply even better.
Any specialised low noise or HF supplies can be built up specifically for the project.
Andrew,
I like your idea would an old HP 6205C do the job and meet the requirements you set fourth? And if not do you have a recommended unit that I might look for? I would not be opposed to building from scratch if necessary.
I know I want:
Dual
30 - 50V Variable
Variable Amperage
This should cover most of my future needs?
Cheers
I like your idea would an old HP 6205C do the job and meet the requirements you set fourth? And if not do you have a recommended unit that I might look for? I would not be opposed to building from scratch if necessary.
I know I want:
Dual
30 - 50V Variable
Variable Amperage
This should cover most of my future needs?
Cheers
For several years now I use a "cheap" chinese made psu.
2 x 0..30V @ 5 Amps.
It saved me a lot of components during test.
It made trouble shooting an amp a lot more relax, knowing that it it will not burst into flames with every mistake...
Allthough the 30Volts is a serious restriction if you have to test (or build) amps that sometimes need a suply of +/- 100 plus volts.
A good project would be such a psu. +/- 120V @ 1 or 2 amps.
I haven't come across such a schematic.
Buying one is tremendeous expensive. And most of us have the parts laying around.
Knowledge of designing such a beast is "someting else" (Eddy Cochran - http://www.youtube.com/watch?v=UW659x8T-oo&feature=related)
IF some one has a nice example, pls...
Cheers
2 x 0..30V @ 5 Amps.
It saved me a lot of components during test.
It made trouble shooting an amp a lot more relax, knowing that it it will not burst into flames with every mistake...
Allthough the 30Volts is a serious restriction if you have to test (or build) amps that sometimes need a suply of +/- 100 plus volts.
A good project would be such a psu. +/- 120V @ 1 or 2 amps.
I haven't come across such a schematic.
Buying one is tremendeous expensive. And most of us have the parts laying around.
Knowledge of designing such a beast is "someting else" (Eddy Cochran - http://www.youtube.com/watch?v=UW659x8T-oo&feature=related)
IF some one has a nice example, pls...
Cheers
Hi,
If you understand french, here is an example of "configurable" supply, adaptable from 12V to 300V max voltage, and 1 to 50A max current.
The values shown in example are 50V/2A:
http://forums.futura-sciences.com/thread169277.html
Here is another one, more complete, but with fixed features 30V/5A:
http://forums.futura-sciences.com/thread68386.html
LV
If you understand french, here is an example of "configurable" supply, adaptable from 12V to 300V max voltage, and 1 to 50A max current.
The values shown in example are 50V/2A:
http://forums.futura-sciences.com/thread169277.html
Here is another one, more complete, but with fixed features 30V/5A:
http://forums.futura-sciences.com/thread68386.html
LV
If you want to build one, start with a simple LM317/337 based supply. If you need more current you can use pass transistors to increase the 317/337's current handling.
You will very rarely need tons of current, as you are only testing the amp when you put it on a bench supply - you are not trying to drive speakers. Once you have the amp working OK on a bench supply, you would connect up it's regular supply to do proper testing with.
You may also want to look at getting a Variac for when you need to bring up an amp's power supply slowly.
You will very rarely need tons of current, as you are only testing the amp when you put it on a bench supply - you are not trying to drive speakers. Once you have the amp working OK on a bench supply, you would connect up it's regular supply to do proper testing with.
You may also want to look at getting a Variac for when you need to bring up an amp's power supply slowly.
I have a 20 Amp Variac that I can mount to my bench so if I already have that then how much of a PSU is necessary for 90% of all DIY audio and electronics. If you can not tell by the questions ........ this is my first project.
: )
Cheers
: )
Cheers
Go with the LM317/337 for starters - it's easy and fairly cheap to make. Maybe use MJ15003/4 or similar as pass transistors to give you a bit more current handling. Read the data sheet for the chips and you will see what I mean.
edit: Actually the National Data sheet shows a nice schematic - a 5A constant voltage/constant current controllable PSU. I would imagine you could adapt the same circuit for the 337.
edit: Actually the National Data sheet shows a nice schematic - a 5A constant voltage/constant current controllable PSU. I would imagine you could adapt the same circuit for the 337.
A Bench Power supply is a better "BUY" vs "MAKE" decision -- there are always HP, Lamda, Heath and Eico supplies for very low bucks and you get the meters, current limiting, transformer and chassis. HP 6205, Heath 2718, 2716 etc...
For amplifier testing I use a pretty beefy Hewlett Packard supply from which I removed the innards, replaced with a Variac, 500VA Stepper Motor toroid, MUR860 diode bridge and 27mF filtration. The supply retained the meters which can be switched from the pos or neg side.
Back in the days of the dot-com bust, HP Power Supplies went for pennies on the dollar:
For amplifier testing I use a pretty beefy Hewlett Packard supply from which I removed the innards, replaced with a Variac, 500VA Stepper Motor toroid, MUR860 diode bridge and 27mF filtration. The supply retained the meters which can be switched from the pos or neg side.
Back in the days of the dot-com bust, HP Power Supplies went for pennies on the dollar:
An externally hosted image should be here but it was not working when we last tested it.
Hi Jaycee, My circuit revolves around that concept... of LM+power transistor.
HOWEVER, the datasheet is deceptively simple about this.
It does indicate a minimum load (which is quite high, 20 or 30mA if memory is working).
Now imagine you try to make a supply variable between 32 and 16V.
If you set the load while at 32V you will only have half the required load when you get to 16V.
When you set it while at 16V you have double the current when you get to 32V leading to some sick dissipation and temperatures according to my simulation.
It is not realy a problem when it is powering something, but when the output is left open things get "unsafe"
HOWEVER, the datasheet is deceptively simple about this.
It does indicate a minimum load (which is quite high, 20 or 30mA if memory is working).
Now imagine you try to make a supply variable between 32 and 16V.
If you set the load while at 32V you will only have half the required load when you get to 16V.
When you set it while at 16V you have double the current when you get to 32V leading to some sick dissipation and temperatures according to my simulation.
It is not realy a problem when it is powering something, but when the output is left open things get "unsafe"
Hmm yes, i didn't spot that.
What do you think of the "5A Constant Voltage/Constant Current Regulator" circuit in the same data sheet?
You dont see many good schematics for bench supplies even though I'd warrant every electronics hobbyist has wanted to build one in some fashion!
What do you think of the "5A Constant Voltage/Constant Current Regulator" circuit in the same data sheet?
You dont see many good schematics for bench supplies even though I'd warrant every electronics hobbyist has wanted to build one in some fashion!
Would the 6205C suit most diy audio and electronics needs if I already have a 20amp Variac? Or should I look for something else.
Gavinator68 said:
It will suit most of your low-current needs -- working on opamps etc.,
There is an analog to the 6205 from Lambda but I don't see any available at the moment...and you won't feel guilty if you get a Heath supply and have to take it apart and put it back together again...
For working through a power amplifier -- let's say you're trying to build a 200W design -- you are probably going to have to go the Variac/Transformer/Bridge/Filter route -- a regulated supply just burns up "watts" -- the Variac is more efficient. There are switching lab supplies by Sorensen and others, but these tend to be a couple hundred bucks and are usually just one polarity (so you need two).
Since you are in Virginia, you might want to check out the Government Surplus website -- there is an equipment depot in your neck of the woods -- but you might have to purchase a pallet of equipment and move it with a forklift.
Thank you Jack................ I have built my Dual Mono PSU for the Stereo P101 I am trying to finish putting together. But if I understand you correctly then if I want to design amps from scratch in the future then I will need a variac/tranny/bridge/filter set-up to make my life easier? Rather than building the psu first then designing and tweaking the amp after. Correct?
Cheers
Cheers
Well, I would build the amplifier testing power supply first --
If you can purchase a professional amplifier -- like a Crown 300 -- something which some rocker used with working transformer and shot transistors -- you can refashion it -- with variac -- to test your amplifier -- all you need is the case, trafo, filter caps -- sometimes you can pick up a Crown or Peavey etc. for cheap.
Below is a shot of the HP carcase I use. It's from an HP6130 Digital Voltage Source. Inside is something like a 400VA transformer, about 39mF perside of filtering and an MUR860 Diode Bridge:
For the preamplifier stuff I have been working on I use a Tektronix PS5010 -- these have been getting pricey and finding one without issues is difficult. For Tube Stuff I use a Heath Supply -- the same one I used for the vacuum tube curve tracer - it's programmable !
If you can purchase a professional amplifier -- like a Crown 300 -- something which some rocker used with working transformer and shot transistors -- you can refashion it -- with variac -- to test your amplifier -- all you need is the case, trafo, filter caps -- sometimes you can pick up a Crown or Peavey etc. for cheap.
Below is a shot of the HP carcase I use. It's from an HP6130 Digital Voltage Source. Inside is something like a 400VA transformer, about 39mF perside of filtering and an MUR860 Diode Bridge:
An externally hosted image should be here but it was not working when we last tested it.
For the preamplifier stuff I have been working on I use a Tektronix PS5010 -- these have been getting pricey and finding one without issues is difficult. For Tube Stuff I use a Heath Supply -- the same one I used for the vacuum tube curve tracer - it's programmable !
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