One shot pulse needed

Thread Starter

daytona

Joined Jan 15, 2021
41
I have a 120 Vac, from a relay, that when it turns on I need to short two wires for approx. 3 seconds. How can I do that.
The circuit needs to reset a digital readout by shorting 2 pins on the readout. I was using a timer relay with delay off of 3 sec but we can no longer buy the brand that we were going to use.
 

Yaakov

Joined Jan 27, 2019
3,464
I have a 120 Vac, from a relay, that when it turns on I need to short two wires for approx. 3 seconds. How can I do that.
The circuit needs to reset a digital readout by shorting 2 pins on the readout. I was using a timer relay with delay off of 3 sec but we can no longer buy the brand that we were going to use.
There are so many time delay relays on the market you can find whatever you want. Is there some reason you don't want to?

Of course if you want to build it yourself, the 555 is the classic answer.
 

Thread Starter

daytona

Joined Jan 15, 2021
41
There are so many time delay relays on the market you can find whatever you want. Is there some reason you don't want to?

Of course if you want to build it yourself, the 555 is the classic answer.
I think we are over budget. we just had 50 high high dollar 12v batteries stolen that we have to replace. I will look into a 555, whatever that is.
 

Yaakov

Joined Jan 27, 2019
3,464
I think we are over budget. we just had 50 high high dollar 12v batteries stolen that we have to replace. I will look into a 555, whatever that is.
The 555 is anIC that can be used for all sorts of things, including interval timing. It's cheap, easy to use, and requires just a few external parts.
 
Last edited:

AnalogKid

Joined Aug 1, 2013
9,351
Are there any low voltage DC sources to power a timer circuit, or is everything 120 Vac?

If you want the time delay device / circuit / whatever to be powered by the switched 120 Vac, this *might* done with an optical coupler, a diode, and some resistors and capacitors. It depends on the characteristics of the thing being switched. Can you post a manufacturer's link, user manual, etc?

Does this sound like something you can handle? I ask because not knowing what a 555 is tells us a lot about your experience level. That is not a dig in any way; it's just that what you can and cannot do sets boundaries on what we can and cannot suggest.

ak
 

Thread Starter

daytona

Joined Jan 15, 2021
41
Are there any low voltage DC sources to power a timer circuit, or is everything 120 Vac?

If you want the time delay device / circuit / whatever to be powered by the switched 120 Vac, this *might* done with an optical coupler, a diode, and some resistors and capacitors. It depends on the characteristics of the thing being switched. Can you post a manufacturer's link, user manual, etc?

Does this sound like something you can handle? I ask because not knowing what a 555 is tells us a lot about your experience level. That is not a dig in any way; it's just that what you can and cannot do sets boundaries on what we can and cannot suggest.

ak
Thanks for the help. No offense taken, I know my limits. I am the quality manager not an electronic engineer. I could eventually figure it out but would take way too much time away from my duties. Yes there is 12Vdc available but my switched voltage is120Vac so I would have to put a relay in to switch the 12V or another device. As far as the device all I need to do is short two terminals for 3 seconds and that will reset the display. We probably need to just find a cheap timer. I have 7 timers in the unit now and I told the boss to buy a cheap "off delay" timer and I will move the others that we already have to do the more important duties like re-triggerable one shot. I found out that the issue is that we can't get the desired timers in time to ship on schedule.
 

Thread Starter

daytona

Joined Jan 15, 2021
41
Hi daytona, welcome back.
Here's a module that uses a 555 timer chip that will get the job done. You will need to supply a 12 volt DC adaptor to power the module and the adaptor will be powered by the 120VAC from the relay.
https://www.amazon.com/Seconds-Modu..._rhf_dp_s_pop_multi_srecs_sabr_4?pd_rd_w=6ZFC

View attachment 237074


EDIT: previous module I posted was a delay before on timer I think.
Thanks, that is an awesome device already made. Price is good also.
 
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