Hello,

I am trying to design a circuit that allows me to switch between 110ac and 24vdc. My question: can i put diodes on the output of the fwb to limit the reverse current when its on 110ac. how can i ensure the diode doesn't fail on me? is a resistor needed with the diode? and what type of diode would best suit this circuit?

Thanks in advance for any information/tips

 

D2 will be blocking in the DC mode.
Max.

 

Why are mixing AC and DC onto the same output wires?

 

Why are mixing AC and DC onto the same output wires?

The output wires will be going into the coil terminals of a relay socket. i want to be able attach ac/dc relays to the same socket.

D2 will be blocking in the DC mode.
Max.

Thanks for the help. after removing D2 on MultiSim i am getting about 45vac through the fwb when on AC mode.
would the 45v cause any problems to fwb? any other suggestions the prevent this? thank you once again

 

Why not just move the switches to the junction of the 110 and 24 supplies, just above where d2 and d3 were on your second drawing. Don't switch where the 110 source is headed (straight to relay vs into transformer.) Instead, allow 110 into transformer at all times and just switch relay coil between 110 and 24v rectifier output. Sorry no time to draw what I mean. Does the description make sense?

 

The proposed arrangement is hazardous. If S1 and S2 got flipped accidentally a 24V load could suddenly become live! Use separate sockets for the 110V and 24V relays; or else use a mains isolating transformer.

 

Why not just move the switches to the junction of the 110 and 24 supplies, just above where d2 and d3 were on your second drawing. Don't switch where the 110 source is headed (straight to relay vs into transformer.) Instead, allow 110 into transformer at all times and just switch relay coil between 110 and 24v rectifier output. Sorry no time to draw what I mean. Does the description make sense?

Thanks a bunch. the circuit attached is what i understood from your description, which should work. the switch in the circuit will be a 2 pole 4 position rotary switch. with this i should have no problems adding another output like 110vdc correct?

 

Thanks a bunch. the circuit attached is what i understood from your description, which should work. the switch in the circuit will be a 2 pole 4 position rotary switch. with this i should have no problems adding another output like 110vdc correct?

View attachment 85940

That's what I had in mind. Also, I believe this arrangement makes d2 redundant and unnecessary.

Depending on the intended purpose of c1, does it need to move? Do you want it there for dc output stability or for back emf absorption?

Finally, Alec_t brings up a good point (and is far wiser and more experienced than I am.) You may want to reconsider this entire concept for safety reasons. Don't let my advice serve as tacit endorsement of any connections to live mains voltage. When in doubt, take no chances!

 

Welcome to the AAC forum.

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This thread is against the AAC forum rules, Terms of Service (ToS).

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Good luck.