Questions on smps

[Ashroyer05]

If there are relays on the primary side before the filter caps are those used in place of a stepdown transformer? When the power supply receives signal to switch on where is the first place that signal goes to (transistor, regulator, etc)?
After the signal is sent does it go all the way back to the primary side before the supply can switch on or does it get sent to a transformer on the secondary side to step the voltage back up? If I have different ic's with pretty close voltages for Vin and Vout would they be run from the same transformer circuit or would they be run off separate transformers. This supply I am working on now has 5 transformers on it. It supplies 3.3V, 6V and 50-90 DC. It actually looks like the mains plug, then a couple relays, then a transformer, then the filter caps. I think this thing is overly complicated in design.

[JonathanAnon]

Re: Questions on smps

Could you post images of the circuit that you are talking about...

In larger TV power supplies there is a standby circuit, which powers the LED at the front of the TV and powers the circuit that accepts responses from the remote control... When you press the ON button on the remote control the standby circuit triggers the mains relay to turn it on, which powers up the other circuits.. When you switch OFF the TV you will hear the relay clicking off, cutting power to the main circuits and leaving only the standby circuit running.

So essentially the relay just operates like an electronically controlled switch to switch the power on and off in response to your commands from the remote control.

[budm]

Re: Questions on smps

"This supply I am working on now has 5 transformers on it. It supplies 3.3V, 6V and 50-90 DC. It actually looks like the mains plug, then a couple relays, then a transformer, then the filter caps. I think this thing is overly complicated in design."
Boy, you just keep posting questions all over the places.

https://www.badcaps.net/forum/showth...913#post425913
https://www.badcaps.net/forum/showth...936#post425936
https://www.badcaps.net/forum/showthread.php?t=35505
https://www.badcaps.net/forum/showthread.php?t=35415
https://www.badcaps.net/forum/showthread.php?t=35416
https://www.badcaps.net/forum/showthread.php?t=35578

[budm]

Re: Questions on smps

This one is already explained it:
https://www.badcaps.net/forum/showthread.php?t=35505
And here is the example of power supply with power relays: PS_ON signal for this one is Active LO.