using tactile switch to operate relay, questions

Thread Starter

bobiowa

Joined Jan 25, 2022
19
I am wanting to use a tactile switch to trigger a relay in a car. The switch is rated at 50ma and the relay draws up to 450ma on activation.

I am wanting to trigger this by connecting the relay to 12v on one lead and then the other lead would go to one side of the tactile switch with the other on the tactile switch going to ground. I did take a multimeter and connect it between the ground on the car battery and the ground lead of the relay and it indeed shows 437ma momentarily while activating and then goes to open (so i am assuming this is a latching relay)

I really dont want to smoke this switch so wondering what my options might be? Would appreciate any idea's

Thanks!
Bob
 

eetech00

Joined Jun 8, 2013
3,154
I am wanting to use a tactile switch to trigger a relay in a car. The switch is rated at 50ma and the relay draws up to 450ma on activation.

I am wanting to trigger this by connecting the relay to 12v on one lead and then the other lead would go to one side of the tactile switch with the other on the tactile switch going to ground. I did take a multimeter and connect it between the ground on the car battery and the ground lead of the relay and it indeed shows 437ma momentarily while activating and then goes to open (so i am assuming this is a latching relay)

I really dont want to smoke this switch so wondering what my options might be? Would appreciate any idea's

Thanks!
Bob
You need a higher current switch, at least a 750mA DC switch.

Its either energized or de-energized so not a latching solenoid.

Datasheet attached
 

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sghioto

Joined Dec 31, 2017
3,288
A more comprehensive description of what this Solenoid does
I think the TS wants to incorporate the Mac Valve assembly in a turbo boost for a vehicle.
From my understanding the solenoid is PWM controlled by the ECU with maybe a in line switch to disconnect when required.
1643225171851.png
 

Thread Starter

bobiowa

Joined Jan 25, 2022
19
Sorry guys, was trying to not overwhelm with details I didnt think you would want, i'll provide some more info..

what i am doing is installing a shifter handle out of a european car into an old hotrod that has two switches embedded into it. I have found what appears to be exact matches of those switches on C&K's switch site (they are rated at 50ma). one of the switches will trigger via ground a relay that is part of the MAC valve (35A-AAA-DDBA-1BA) the relay on the valve shows on the label 5.4 watts.

the idea is that i will push the tactile switch which will engage the relay (only as long as i have the switch pushed). This will in turn open the MAC valve's piston which will let air into an air cylinder which will push down on a rod to allow the shifter to unlock so it can come out of park.

i have considered using a 12v relay in front of this relay but not sure if that would work

fwiw..
i am using the following board on the other switch (which appears to work fine) which turns on a rearview camera through the radio. https://www.amazon.com/ELECTRONICS-...ords=Electronics-Salon&qid=1643229483&sr=8-52

only reason i didnt use the same board on the switch i am inquiring about is because this board has a latching relay so one push of the button turns relay on or off.
 

Thread Starter

bobiowa

Joined Jan 25, 2022
19
haha sorry, im more of a fabricator than a electrical guy ( i have alot to learn ). So would a generic automotive 30 amp relay ahead of the mac valve do the trick or should i be looking at that circuit board?
 

sghioto

Joined Dec 31, 2017
3,288
So would a generic automotive 30 amp relay ahead of the mac valve do the trick or should i be looking at that circuit board?
Those 30 amp relays usually draw more then 100ma to activate so you would still need the relay module unless you want to build your own circuit using a transistor.
 

Thread Starter

bobiowa

Joined Jan 25, 2022
19
I wouldnt have the first clue on how to do that, so it looks like your suggestion on the board is a great , affordable solution. Thanks everyone for all the input. I'm going to order the board and give it a shot.
 

LowQCab

Joined Nov 6, 2012
2,052
Interfacing the Switch is easy, but you've got a real "Rube-Goldberg-Device" in the making.
There are far more simple ways of Theft-Proofing your Car.

If it's going to be stolen, it will be stolen by a proper Tow-Truck,
and the driver doesn't care if your Car is locked in Park, makes no difference to him.

What type of Transmission are You using ?
What's the overall end result that You hope to accomplish ?
.
.
.
 

Thread Starter

bobiowa

Joined Jan 25, 2022
19
Appreciate the concern but luckily has nothing to do with theft proofing the car. :)Just adding european elements to an interior refresh on an old car and trying to keep the current shifter locking mechanism in place for basic safety reasons.
 

panic mode

Joined Oct 10, 2011
2,134
I am wanting to use a tactile switch to trigger a relay in a car. The switch is rated at 50ma and the relay draws up to 450ma on activation.
so use a transistor to operate relay. that ways small current through switch can simply drive transistor that turns on relay.
today you get plenty of candidates - mosfet or bipolar... or use IC such as ULN2003. this is cheap and least complicated.
Here button current is only some 10mA even though all inputs are paralleled. at the same time outputs are paralleled too and could drive even much larger relay or contactor. This option only needs one very low cost part and wiring could not be simpler. even suppression diode diode is already included.

1643250058611.png
 
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