Circuit of NCTO delay relay using 555 timer

Thread Starter

skpmech

Joined May 15, 2017
8
I want to make a normally closed time open delay relay using 555 timer. I want a time delay of about 2 seconds. Please post with proper circuit diagram as I am not so familiar with electronics as I am a mechanical engineer. Thank you.
 

Thread Starter

skpmech

Joined May 15, 2017
8
Depending on how you want to trigger it.. Make the 47K resistor on pin7 a 22k pot, with a 1k in series ..


View attachment 126917

There are several designs.....
Actually the motor will run continuously and after a dealt of 2 second relay should triggered and open the circuit so that motor will not run until main power supply is off. Timer will reset when main PS is off.

But how to calculate time delay? Can you provide the detailed circuit? I also don't know how to wire relay. Help is highly appreciated. Thank you
 

Tonyr1084

Joined Sep 24, 2015
6,077
what is the role of 22K pot
Adjustability. You can dial in the exact time you want the delay to be.

Quick question for you: You want the motor to run for (oh, lets say) 2 seconds then shut down until power is recycled? Or do you want the motor NOT to run for 2 seconds then start up afterwords?
 

Dodgydave

Joined Jun 22, 2012
10,041
Means changing 100uf capacitor and 2K resistor can vary the delay time right? But then what is the role of 22K pot Mr. Dodgydave is saying about?
No! 100 uF capacitor and the 47K resistor,

if you want 2seconds then you need 100uF cap and 20K resistor, so i would put a 22K preset and a 10k resistor in series to give you better results.


004_03.gif
 

Thread Starter

skpmech

Joined May 15, 2017
8
Adjustability. You can dial in the exact time you want the delay to be.

Quick question for you: You want the motor to run for (oh, lets say) 2 seconds then shut down until power is recycled? Or do you want the motor NOT to run for 2 seconds then start up afterwords?
Yes I want the motor to run for 2 seconds then shut down until power resets.
 

Tonyr1084

Joined Sep 24, 2015
6,077
Why 2 seconds? Can you live with 4 or 5 seconds or slightly longer? How tightly are you constrained to 2 seconds?

[edit] Well I suppose that's a moot point. With the circuitry DodgyDave gave you - that should solve your problem. You can precisely dial in the delay with the pot.
 

Thread Starter

skpmech

Joined May 15, 2017
8
Why 2 seconds? Can you live with 4 or 5 seconds or slightly longer? How tightly are you constrained to 2 seconds?

[edit] Well I suppose that's a moot point. With the circuitry DodgyDave gave you - that should solve your problem. You can precisely dial in the delay with the pot.
Yeah 2 second is not necessary 5 seconds will work fine.
 

Tonyr1084

Joined Sep 24, 2015
6,077
Here's a circuit I built a long time ago. Have a truck (standard transmission) with cruise control. The transmission would not shift down on its own when the load got too heavy, so I put in a vacuum gauge to know when the load was too heavy, and I could shift down. The gauge had a memory and you could set the color to match your gauges. Every time I started the truck the gauge would light up then default to the factory color. Hated having to choose the color every time I started the truck. So I built this circuit to delay the onset of power going to the gauge. Delay was about 4 seconds. You can use this to incorporate the relay as a delay ON or a delay OFF.

[edit]
And yes, I used a 24 volt relay. At 13.6 volts it would easily click in. You may want to modify the circuit to suit your needs, but this is a very cheap base to start from without having to build the 555 timer circuit. The advantage here is there are no IC's to be harmed by Electro Static Discharge. Oh, and the relay is shown in the energized position.

Time Delay Start.png
 
Last edited:

Tonyr1084

Joined Sep 24, 2015
6,077
Followup thought on the circuit I provided: if you're powering the relay from a low voltage source such as 12 volts and want to switch a motor running at high volts AC then the relay you'll want to use will have to be a double pole double throw type so you can isolate the high voltage from the low control voltage circuitry.
 

Thread Starter

skpmech

Joined May 15, 2017
8
Followup thought on the circuit I provided: if you're powering the relay from a low voltage source such as 12 volts and want to switch a motor running at high volts AC then the relay you'll want to use will have to be a double pole double throw type so you can isolate the high voltage from the low control voltage circuitry.
But your circuit isn't using 555 IC. I want to built whole circuit with 555 IC only. Thanks for advice.
 
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