I figured it out. I was using the center tapped transformer in the wrong way. Definitely a newbie mistake.
Could somebody explain the purpose of C3 please? (Not questioning it... Just for my general understanding of the circuit). From what I can see the zener diode takes the rectified AC and regulates it to coil voltage. Does C3 filter it further?
Cheers,
Tim
Cheers,
Tim
OK. I seen the resistors and capacitors circuit previous to the bridge as the delay, but that makes sense now. I guess C3 charge time is an added delay as well. Thanks 🙂
Increase delay time
Hello all,
I have a 300va transformer and my mains ac is 120v. What value do I need C3 to be in order to delay the soft start to roughly 10-15 seconds?
Hello all,
I have a 300va transformer and my mains ac is 120v. What value do I need C3 to be in order to delay the soft start to roughly 10-15 seconds?
why such a long delay? a 60hz cycle has 0.016 seconds. so that 1 second delay has 60 periods, more than enough i would say....
i get by with just an ntc resistor in series with the power traffo primary...
cold resistance of about 5 ohms and below 1 ohm when heated up...
The soft start is not a delay timer. It can't be rigged for times that long.
If you could delay the B+ that long, it's because you have a seperate transformer for the heaters... so why not just put them on a 3-position switch? Off - heater - B+&heater
If you could delay the B+ that long, it's because you have a seperate transformer for the heaters... so why not just put them on a 3-position switch? Off - heater - B+&heater
i got these three way rotary switches, with an on/off switch built in,
so that the on, standby, and operate modes can be achieved...
to ensure long life, i will use relays to turn on transformers and switch off B+ ramping resistors...
Thank you
Thank you! I was hoping to purchase the soft start from here but I guess I will just purchase a delay kit elsewhere.
Thank you! I was hoping to purchase the soft start from here but I guess I will just purchase a delay kit elsewhere.
K&K Audio sells a nice little delay board, there is also a softstart/delay version but i haven't used that one myself.
Test your transformer wiring first.
Build a Mains Bulb Tester to help prevent blowing up your project due to miswiring the PSU.
Build a Mains Bulb Tester to help prevent blowing up your project due to miswiring the PSU.
Andrew, is it wright ? Thanks !
An externally hosted image should be here but it was not working when we last tested it.
Build a Mains Bulb Tester.
Test your transformer first.
Then add on the rectifier.
Test the transformer+rectifier.
Then add on the smoothing capacitor/s.
Test the transformer plus rectifier plus smoothing capacitor.
Get the idea?
The bulb filament acts as the added resistance of the soft start.
Eventually you need to test your soft start.
It is safer to test the soft start via the mains bulb tester, but this doubles the added resistance and a poor timer design may not trigger the bypassing relay and the soft start resistor does not get bypassed. Do this test quickly to prove your wiring is OK and switch off to let the resistor cool.
Then test the soft start with the project direct to the mains. The fuse should not blow.
If you have a properly designed timer in your soft start bypass then you won't have any problem of getting the relay to trigger.
You are missing the Mains fuse.
It is the first thing in the mains wiring - before the switch.
C1 is in the wrong place.
As shown it bypasses the switch, so that you can never switch off your equipment !
The bypass timer is direct to mains powered. We are not allowed to discuss this !
Test your transformer first.
Then add on the rectifier.
Test the transformer+rectifier.
Then add on the smoothing capacitor/s.
Test the transformer plus rectifier plus smoothing capacitor.
Get the idea?
The bulb filament acts as the added resistance of the soft start.
Eventually you need to test your soft start.
It is safer to test the soft start via the mains bulb tester, but this doubles the added resistance and a poor timer design may not trigger the bypassing relay and the soft start resistor does not get bypassed. Do this test quickly to prove your wiring is OK and switch off to let the resistor cool.
Then test the soft start with the project direct to the mains. The fuse should not blow.
If you have a properly designed timer in your soft start bypass then you won't have any problem of getting the relay to trigger.
You are missing the Mains fuse.
It is the first thing in the mains wiring - before the switch.
C1 is in the wrong place.
As shown it bypasses the switch, so that you can never switch off your equipment !
The bypass timer is direct to mains powered. We are not allowed to discuss this !
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