Using resistor in sense line to increase range of regulated supplY? - diyAudio
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Old 10th December 2008, 08:31 PM   #1
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Default Using resistor in sense line to increase range of regulated supplY?

Hi, folks-
I've been lurking here for a while- fantastic source of info- thanks to everybody.
I need some some advice, please.

I've got a pair of Hammond 24volt regulated DC supplies that I'm thinking of using to power some chipamp experiments.
The adjusting pot on the PCB controls the regulated output between about 22-26 volts when the + sense is connected to the + DC out terminal.
Unregulated (sense disconnected) output is 39v.
Supply is rated at 5A DC. Transformer is 55vac CT.

I'd like to increase the output voltage range to something in the 25-35v range, without hacking into the PCB.
Putting a 1k resistor in the sense line seems to give me a regulated output near 35v. (The resistor is 'tricking' the regulator into thinking that there's a voltage drop in the + line ?)
Does anybody see a problem with wiring up a resistor like this, so I can switch between 25v and 35v output?
It seems to work fine when loaded with a resistor and putting out about 5W.

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Old 11th December 2008, 01:02 PM   #2
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You should check it under full load at 35v because the voltage might drop below that.
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Old 12th December 2008, 10:50 AM   #3
Bakmeel is offline Bakmeel  Netherlands
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The resistor in the sense line is fine, but also do check if the other components in the output can withstand 35V. For example, caps and protection devices can fail if they're subject to voltages above their rating.
More Power Igor! More Power!
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Old 12th December 2008, 07:54 PM   #4
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Thanks for the replies.
Like most of the Hammond stuff I've seen, these PS units are pretty hefty units- the caps are 60v rated and the transformers are quite large.
Once I build a case strong enough to support them, I should be set for power for the chipamps.
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