HELP! How to add a delay "on" time to a coil

mrsodapop

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HELP! How to add a delay "on" time to a coil

Hi all,
I am actually working on a pop machine and have to replace the old dispense relays (from 1960s?). OE replacements do not exist, so I have to use a newer style, but the coils on the relays need to stay on for about 1 second. Does any body know how to get the coil to hold the relay open for about 1 second? Right now when I press the vend button, the coil on the relay will only stay "on" for a small fraction of a second, not long enough to open the can release coil all the way. The relay coil gets a quick 40vac to work. The old coil/relay used a capacitor(I believe) to accomplish this, and I have tried a few different capacitors on the new ones, but with no luck.

Thanks for any ideas!
Aaron
 
Thanks for the ideas, but I would need 4 relays, and at $50 bucks each+ my time for a $300 machine, the owner would not go for it. I like the idea of the 555 IC, but again it would require at minimum adding a power supply, and some other wiring. I would like to do as little mods to the machine as possible.
Thanks again, and keep the ideas coming
Aaron
 
Thanks for the ideas, but I would need 4 relays, and at $50 bucks each+ my time for a $300 machine, the owner would not go for it. I like the idea of the 555 IC, but again it would require at minimum adding a power supply, and some other wiring. I would like to do as little mods to the machine as possible.
Thanks again, and keep the ideas coming
Aaron

Do you have a wiring diagram for this issue?
 
I'll have to go back out and look at model #, but here is pics of original relays
 

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I would find the model of the machine and then post over at Soda-machines forum.. There are a few guys that do service and have for quite awhile. Someone may have an idea about them.
 
The relay coil gets a quick 40vac to work. The old coil/relay used a capacitor(I believe) to accomplish this, and I have tried a few different capacitors on the new ones, but with no luck.

The capacitor trick won't work with AC -- the cap won't change, and will instead "smooth" away the AC and the relay may not close at all. If the new relay will work with DC, you could try rectifying the input and feeding a (big) capacitor with that.
 
The capacitor trick won't work with AC -- the cap won't change, and will instead "smooth" away the AC and the relay may not close at all. If the new relay will work with DC, you could try rectifying the input and feeding a (big) capacitor with that.

If the relay still doesn't hold long enough you might want to try putting a resistor in between the Capacitor and the relay you would be creating a RC circuit. Slowing down the discharge of the the capacitor.
 
Hi All,
I finally got a chance to try out some of your suggestions. Unfortunately still can't get relay to stay closed long enough. I first tried adding a diode (1N4007) This actually helped a little, went from a fraction of a second to about 1/2 second( still not quite long enough). I than tried several different Caps 10uf-1000uf with no change, I than put a few different 2w resistors in, with no change. I also found after looking closely at the wiring diagram of the power being supplied to vend coil is 120vac not 40vac(my meter was just too slow to register all of the short pulse of voltage). I have access to some Allen Bradly delay relays(120vac), that I will try out in the next day or two.
I also signed up with soda-machines.com, but have yet to get my blessing to start posting.
Thanks a lot for all the ideas so far
Aaron
 
You know maybe we are looking at this from the wrong end.
Can you tell us what is sending that 120 volts down to the relay?
maybe we can add the delay into the control side..

If One diode will give you 1/2 a second with just half a Pulse of ac and 1/2 second
A full bridge will give will five you two pluse in the same time that might give you that second you need.
 
Last edited:
Hi All,
I finally got a chance to try out some of your suggestions. Unfortunately still can't get relay to stay closed long enough. I first tried adding a diode (1N4007) This actually helped a little, went from a fraction of a second to about 1/2 second( still not quite long enough). I than tried several different Caps 10uf-1000uf with no change, I than put a few different 2w resistors in, with no change. I also found after looking closely at the wiring diagram of the power being supplied to vend coil is 120vac not 40vac(my meter was just too slow to register all of the short pulse of voltage). I have access to some Allen Bradly delay relays(120vac), that I will try out in the next day or two.
I also signed up with soda-machines.com, but have yet to get my blessing to start posting.
Thanks a lot for all the ideas so far
Aaron

You should have gotten an activation email immediately. Check your spam folder. If you didn't get a message, let me know the username you registered under an email address and I'll get you taken care of.
 
Hi All,
I finally got a chance to try out some of your suggestions. Unfortunately still can't get relay to stay closed long enough. I first tried adding a diode (1N4007) This actually helped a little, went from a fraction of a second to about 1/2 second( still not quite long enough). I than tried several different Caps 10uf-1000uf with no change, I than put a few different 2w resistors in, with no change. I also found after looking closely at the wiring diagram of the power being supplied to vend coil is 120vac not 40vac(my meter was just too slow to register all of the short pulse of voltage). I have access to some Allen Bradly delay relays(120vac), that I will try out in the next day or two.
I also signed up with soda-machines.com, but have yet to get my blessing to start posting.
Thanks a lot for all the ideas so far
Aaron

I think you have been blessed and can start posting no9w.
 
I first tried adding a diode (1N4007) This actually helped a little, went from a fraction of a second to about 1/2 second( still not quite long enough). I than tried several different Caps 10uf-1000uf with no change, I than put a few different 2w resistors in, with no change.

You kinda... missed the message. Use FOUR diodes to make a full-wave rectifier, then put a large (start with a few hundred uF and go up) capacitor across + and - on the rectifier, and put a resistor after it on the + side. Then connect your relay to that and experiment with different cap and resistor values until you get the delay you want.

Make sure everything in this circuit is rated at least 120V, btw.
 
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