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need dummy load for PHR-803T diode

C

cyclonite

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Hi all,

Quick question for the electronics experts. I have DDL's PSU which comes with a voltage and amperage adjustment pot. I have a 1 ohm resistor connected in series at the output. I now need to solder on a dummy load so that I can adjust the voltage and amperage before hooking up the PHR-803T. Could someone please recommend a cheap dummy load?? Someone was suggesting using 4 x 14N001 diodes or something like that?


Many Thanks.
 





daguin

daguin

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22788d1249505515-test-load-verification-test-20load01.jpg



Don't forget to tell Rog , "thank you" ;)

Peace,
dave
 
C

cyclonite

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Thank you Rog!!! Thanks daguin :)

Silvershot, didn't know what to search for :( hehehe.

Many thanks all!
 
mfo

mfo

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Or you could just hook up the output of your driver to an ampere meter, which any decent voltmeter/multimeter should have now days?
 
roddenberry

roddenberry

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Here's a cool little build I did this morning, based on our good friend ROG8811's designs...

I decided to put the dummy load circuitry (refer to msg 2 above) in a little plastic project box, so I pulled a few plug sockets, a couple of IN4004 diodes and a 1 ohm resistor and wired them up on a PCB. First thing was my hunt to find a proper 1 ohm resistor. I have plenty of 1/4 and 1/2 W units but needed something more powerful. So I went into my box of power resistors:
powerres.jpg

Who says it's a waste of time to retrieve the boards off old TVs and monitors... LOL!
Then I drilled on the drill press five holes on the sides of the box to make room for the banana plug sockets. I isolated the connectors of the plugs with shrink tubing to avoid shorts.
start1.jpg

After everything was wired, I started working on the board, which I cut-off to size with a dremel cutting disk... it fits perfectly into the project box.
board1.jpg

I left the diode wires a bit longer and soldered them not too tight to help in the heat dissipation. The resistor is a 5 watt unit so its a bit of overkill... :D
Then I wired the board to the plugs and squeezed the components tightly into the box and applied a bit of glue to prevent the board from rattling in the box and avoid possible shorts.
almostdone.jpg

Then I went on the komputor and did a cool little connector identification label. Thanks Rog8811 for that schematic! Voilà:
finalbox.jpg

Total cost of build: about $5, the banana plugs being the most expensive items in the build. The project box is only $1 at the electronics shop where I go. The diodes were $10 for a thousand and the resistor was probably retrieved from a defunct TV years ago.
Robert :D
 
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cyclonite

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roddenberry:

That's a very handy and neat build. Well done and many thanks for sharing with LPF :)
 
C

cyclonite

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Hey I just noticed you're using a 5w resistor. I've got a spare 3w (I think) that looks a bit like yours. I should try using that because I'm getting weird readings on my dummy load now hmm... why did u say that 1/2 or 1/4 watt wasn't sufficient?? What happens if the driver overloads the resistor?

Btw, all the best for your event and hope it all goes well for you.
 
mfo

mfo

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roddenberry said:
I have plenty of 1/4 and 1/2 W units but needed something more powerful.
Click to expand...

Very nice & neat build. Just out of curiosity, why did you need something more powerful than 1/2 Watt?

cyclonite said:
What happens if the driver overloads the resistor?
Click to expand...

It dies...you'll know when it dies. It'll give off a very fowl smell (Kind of smells like burnt plastic), and will be insanely hot to touch (Like burn your flesh hot). I doubt you'll fry a 1/2 Watt resistor though with using it in a test load, unless you're setting the current for Dr. Evil's moon laser...
 
roddenberry

roddenberry

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mfo said:
Very nice & neat build. Just out of curiosity, why did you need something more powerful than 1/2 Watt?
Click to expand...

Thanks! :D Well i figured just to be on the safe side when using the load at the high end of the power scale (if that ever happens) might make the resistor a bit warm so that way it won't ever overheat ! LOL But you're right a 1/2 W unit would have been fine for the purpose i'll use it for.

I also had a 50 watt wirewound on ceramic core 1 ohm resistor but that would have been overkill to the max! :evil:

Robert
 
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