Relays on/off too fast?

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englertracing
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Relays on/off too fast?

Post by englertracing » Sat Nov 14, 2015 1:13 am

ive got a bosch relay, -to terminal 85 + to terminal 86
86 has a toggle switch between it and the battery,
30 is connected to + and 87 is connected to a test light

it all works fine and dandy, but when i operate the switch rapidly the test light will come on while cycling on and off, but if i go to quickly the light works for a few cycles, then just stays out,
if i wait 2 seconds, power on 2 seconds power off 2 seconds, power on 2 seconds, everything is fine
if i flash it every second, like a turn signal might, the light goes out after the first few and wont come back on till i slow down.



any advice??

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Re: Relays on/off too fast?

Post by joe 90 » Sat Nov 14, 2015 3:16 am

Try another test light.


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Re: Relays on/off too fast?

Post by englertracing » Sat Nov 21, 2015 5:52 am

joe 90 wrote:Try another test light.

Relay quits clicking......

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Re: Relays on/off too fast?

Post by joe 90 » Sat Nov 21, 2015 8:07 am

englertracing wrote:
joe 90 wrote:Try another test light.

Relay quits clicking......
Made in china?

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Re: Relays on/off too fast?

Post by Kevin Johnson » Sat Nov 21, 2015 8:39 am

Be sure to save the parts and pass them along to an instructor to use for a class. Good learning exercise.

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Re: Relays on/off too fast?

Post by englertracing » Sat Nov 21, 2015 4:13 pm

joe 90 wrote:
englertracing wrote:
joe 90 wrote:Try another test light.

Relay quits clicking......
Made in china?
A couple are and some were motorcraft.

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Re: Relays on/off too fast?

Post by englertracing » Sat Nov 21, 2015 4:15 pm

Kevin Johnson wrote:Be sure to save the parts and pass them along to an instructor to use for a class. Good learning exercise.
It's for a hobby rocket ignition system.
It works fine for its purpose

Just want to know why when when I tested it it it works fine at 2 seconds on 2 seconds off but won't work at the pace of 1 second on 1 second off.

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Re: Relays on/off too fast?

Post by Kevin Johnson » Sat Nov 21, 2015 5:00 pm

englertracing wrote:
Kevin Johnson wrote:Be sure to save the parts and pass them along to an instructor to use for a class. Good learning exercise.
It's for a hobby rocket ignition system.
It works fine for its purpose

Just want to know why when when I tested it it it works fine at 2 seconds on 2 seconds off but won't work at the pace of 1 second on 1 second off.
You do not specify the voltage level you are using but Bosch (and other common automotive) relays typically operate with 12v coils and Estes (say) systems might only use 9v batteries and relatively low amperage. The coil saturation time is apparently insufficient with faster switching to allow the field strength to overcome the solenoid return spring. You can test this hypothesis by using a charged 12v automotive battery connected directly to the system comprised of the 12v relay, battery, switch, and light and trying your higher cycling rate.

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Re: Relays on/off too fast?

Post by englertracing » Sat Nov 21, 2015 11:04 pm

Kevin Johnson wrote:
englertracing wrote:
Kevin Johnson wrote:Be sure to save the parts and pass them along to an instructor to use for a class. Good learning exercise.
It's for a hobby rocket ignition system.
It works fine for its purpose

Just want to know why when when I tested it it it works fine at 2 seconds on 2 seconds off but won't work at the pace of 1 second on 1 second off.
You do not specify the voltage level you are using but Bosch (and other common automotive) relays typically operate with 12v coils and Estes (say) systems might only use 9v batteries and relatively low amperage. The coil saturation time is apparently insufficient with faster switching to allow the field strength to overcome the solenoid return spring. You can test this hypothesis by using a charged 12v automotive battery connected directly to the system comprised of the 12v relay, battery, switch, and light and trying your higher cycling rate.
Automotive battery or jumper pack.

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Re: Relays on/off too fast?

Post by Kevin Johnson » Sun Nov 22, 2015 12:39 am

englertracing wrote: any advice??
Yes, since this system is unreliable and is used for launching small missiles I would advise starting with all new known-high-quality components and case (assuming there is a metal or plastic case to hold the assembly) and build a new one that is reliable.

If you swap another light in and the relay stops operating at all ("relay quits clicking") then the system is unreliable per se. When you rapidly cycle the toggle and the circuit initially works but then stops working then it is unreliable per se (inherently).

It would be interesting for a lecturer to retain your old system and the two lights and selection of relays that you used and demonstrate to classes how odd failures can be induced with equipment and why they should be wary of them.

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