Gristle McThornbody
- Mar 14, 2012
- 31
- Joined
- Mar 14, 2012
- Messages
- 31
I have a 100 watt model train transformer that I need to upgrade. It is a simple linear PS with an output of about 20 vdc at a max of about 6 amps. There are some simple train movement controls based on timed decay of the output voltage to simulate braking, etc., but these controls are not an issue. It looks like the variable output voltage is controlled directly from a pot to a single 3055 clone, so there's no regulation to speak of.
Unfortunately, this PS has no filtering at all and therefore lots of AC ripple and this causes problems with some train electronics. I want to install a filter cap on the rectifier output and maybe one on the overall output as well to decrease the ripple. However, placing a suitably sized cap on the front end causes the rectifier outlet voltage to increase beyond what the fan and other control circuitry may be able to handle. Regulation is poor to non-existent so the output voltage increases also.
If I place a decently sized cap on the output, it triggers overcurrent protection and shuts down the power supply. So I can't do it from either end. Is there another way to go about reducing the ripple voltage? I don't need it super low, just under a half volt or so.
Unfortunately, this PS has no filtering at all and therefore lots of AC ripple and this causes problems with some train electronics. I want to install a filter cap on the rectifier output and maybe one on the overall output as well to decrease the ripple. However, placing a suitably sized cap on the front end causes the rectifier outlet voltage to increase beyond what the fan and other control circuitry may be able to handle. Regulation is poor to non-existent so the output voltage increases also.
If I place a decently sized cap on the output, it triggers overcurrent protection and shuts down the power supply. So I can't do it from either end. Is there another way to go about reducing the ripple voltage? I don't need it super low, just under a half volt or so.