Newbie working on a project

Thread Starter

Sun Tek

Joined Apr 19, 2016
11
As stated above, I am definitely a newbie to the electronics world but am anxious to learn.
I am working on a project that will be powered by a 9v battery, It will basically power an led after a switch has been triggered. Once triggered, I would like to make the switch inoperable until the "Relay" or switch has been reset, possibly with a key? If the relay has a button type of reset I can modify a lock cylinder to operate it.
What type of relay should I use or is there a switch that I could use to achieve the same operation?

scan0049.gif
 

wayneh

Joined Sep 9, 2010
16,398
There is such a thing as a latching relay. But I'm not sure what you really want to do. Do you just want to light an LED with one switch, which then does nothing and the LED will only turn off with a second switch? Once the second switch has turned off the LED, the cycle can repeat. There are lots of way to skin that cat.

Do you care about switch positions - like a light switch - or do you want to use momentary push buttons?
 

Thread Starter

Sun Tek

Joined Apr 19, 2016
11
That is exactly what I would like to do. I would like to use momentary push buttons for the first switch. I would like to have the second switch tamper resistant, maybe positional, I thought that I could use a lock cylinder to make it work?
 

ScottWang

Joined Aug 23, 2012
6,912
Is the below circuit match what you want?
The led was calculated around 16mA(80% of 20mA) and adjust the R1 to match a exist value.
Push Sw1 to turn on the LED and NC Sw1 to turn off the led, NC Sw1 is a Normal Close Switch.

9VRelaySetAndReset_ScottWang.gif
 

Thread Starter

Sun Tek

Joined Apr 19, 2016
11
Is the below circuit match what you want?
The led was calculated around 16mA(80% of 20mA) and adjust the R1 to match a exist value.
Push Sw1 to turn on the LED and NC Sw1 to turn off the led, NC Sw1 is a Normal Close Switch.

View attachment 104646
I believe so.
I appreciate your help with this; what type of relay would you use in this application?
 

ScottWang

Joined Aug 23, 2012
6,912
You can use any kind of small 9V relay or using a 5V relay + a current limiting resistor.
Current limiting resistor = (9V-5V) / I_relay(1+10%)
 
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