Hi,
I built a simple power supply as per the one on Nuuk's website which has a 50VA 18-0-18 transformer, 4700uF smoothing caps and a series of paralleled polypropylene bypass caps before the above regulators. It's built on stripboard.
http://myweb.tiscali.co.uk/nuukspot/decdun/gainclonepre.html
The idea was to have a two stage reg in which this first stage would put out ~+-21V and the second stage reg to +-15V.
However, after carefully building the (simple) first stage, the damn thing was putting out -22.2V and +21.8. The unloaded DC voltage before the regs was a steady 27.7V both sides.
I'm using 220R and 3K6 1% metal film resistors to set the voltage.
I checked the resistors' values by disconnecting one end - they were within spec. I then bought two new LM regs, and replaced these and the resistors after matching the new resistors with my meter.
Now the voltage is -21.5V and +22.0V...
I'm fairly sure the regs are proper ONsemi devices.
Any tips on what could be the issue? I know it's hard over the net, but I'm stumped. I've even checked for minor current leakage around the regs through rosin between tracks - there's nothing wrong.
Cheers
Stuey
I built a simple power supply as per the one on Nuuk's website which has a 50VA 18-0-18 transformer, 4700uF smoothing caps and a series of paralleled polypropylene bypass caps before the above regulators. It's built on stripboard.
http://myweb.tiscali.co.uk/nuukspot/decdun/gainclonepre.html
The idea was to have a two stage reg in which this first stage would put out ~+-21V and the second stage reg to +-15V.
However, after carefully building the (simple) first stage, the damn thing was putting out -22.2V and +21.8. The unloaded DC voltage before the regs was a steady 27.7V both sides.
I'm using 220R and 3K6 1% metal film resistors to set the voltage.
I checked the resistors' values by disconnecting one end - they were within spec. I then bought two new LM regs, and replaced these and the resistors after matching the new resistors with my meter.
Now the voltage is -21.5V and +22.0V...
I'm fairly sure the regs are proper ONsemi devices.
Any tips on what could be the issue? I know it's hard over the net, but I'm stumped. I've even checked for minor current leakage around the regs through rosin between tracks - there's nothing wrong.
Cheers
Stuey
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