Remote start switch

crutschow

Joined Mar 14, 2008
34,282
Yes, you certainly can use the unused gates.
I only grounded their inputs because you can't leave any inputs floating with a CMOS circuit.

Those are NAND gates so the logic is that only when both inputs are high is the output is low, otherwise the output is high.
If you want to prevent a signal from going through the gate then you keep one input low. This keeps the output high, regardless of what the the other input does.
 

Thread Starter

ProfessorZAPPP

Joined Nov 18, 2015
21
So if I run the circuits main power through one of the 4093s unused gates, and then loop through another of the unused gates in series and then finally to both chips power supply. They will only have power and be 'on' if those gates are high and sensors on!?
 

crutschow

Joined Mar 14, 2008
34,282
So if I run the circuits main power through one of the 4093s unused gates, and then loop through another of the unused gates in series and then finally to both chips power supply. They will only have power and be 'on' if those gates are high and sensors on!?
No.
These are logic gates which perform logic functions. They can only output a mA or so maximum current.
But you can use their outputs to drive a logic-level type MOSFET to control power to another device.

If you tell me the exact inputs and outputs you want (including current levels you want to switch) I can show you a circuit to do that.
 

Thread Starter

ProfessorZAPPP

Joined Nov 18, 2015
21
Okay, well the inputs I have are just normally open contacts from switches. I can run power through them (12v) waiting until they close to complete the circuit.

Reed switches open circuit until car is in gear, then power will flow.
Same goes for handbreak. Both of these inputs are connected together as one.

I want these switches to cutoff the 3 switch decoder if they are closed so that the start operation is stopped. Which is why I was guessing they control a relay that switches the circuits main power.

As far as current levels I am not sure at this point as I have not connected the circuit to the car and measured its consumption but this shouldn't be hard to match
 

crutschow

Joined Mar 14, 2008
34,282
To stop the count, remove the ground connection from the enable/inhibit pin 13 on the CD4017 and connect it to the output from the two reed switches.
Also add a 10kΩ resistor to ground from pin 13.
With that, the counter will not count when the voltage is 12V from either reed switch being closed and will count when both are open and the resistor pulls pin 13 to ground.
 

Thread Starter

ProfessorZAPPP

Joined Nov 18, 2015
21
The stop clock works for all my sensors, thankyou.

only thing left i cant get to work is with debouncing the 12v 'pulse' received the door. i have a debouncer i added for the purpose of switch testing. now i have added it to the final circuit board anyway because the pulses received for the count aren't a clean 12v on/off unfortunately. the start is a short on off, then full 12v for a second. obviously needs debouncing. i beleive i have connected it wrong though. as there will be no switch on the board, how do i add the wired input from the door lock in place of the switch? do i need a transistor? or does it jut go through the capacitor/resistor without switch

i am confused because on the debounce circuit i have, there is a switch that contacts ground to the middle of a capacitor and resistor. when i remove this switch in place of my wired door lock voltage (pulses) is there somewhere it can connect to allow debounce? or will it just need to power a transistor to replace original switch

other than the circuit not being triggered by these pulses, everything else works perfectly, thanks again
 

Thread Starter

ProfessorZAPPP

Joined Nov 18, 2015
21
Basically yes.
when tested with 3 pulses on a breadbaord with pushbutton and debounce circuit it works.

When adding the door lock (3 pulse in car) it dosent work because each individual pulse is not a clean ON then OFF 12v. there is a sort of on off, then ON for a second. so this would need a debounce so the resistor/capacitor could consume that short burst before the initial 12V on for 1 second yes?

Also i am not sure why but my soldered circuit board everything is fixed too and nothing has moved or changed since i had it working last is causeing the 4017 to heat up and prevent normal proceedure. is there an obvious reason for this? i have checked nothing is shorting out, everything is exactly the same??
 
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crutschow

Joined Mar 14, 2008
34,282
Post a schematic of your debounce circuit.

The 4017 likely would only heat up if an output is shorted to V+ or ground, or one of the inputs is left floating.
 

Thread Starter

ProfessorZAPPP

Joined Nov 18, 2015
21

Same circuit except a 10uf cap and no 7417 obviously

i have gone through all of the circuitry and nothing is shorting out any ware, only input i havent connected external power to is pin 13, but that has the pull down resistor to ground. power is only high through that connector when my sensors are closed, but they arent necessary for the count operation to function as i had before.

Could i have fried the 4017 in the process of testing in my vehicle and maybe this is causing it to heat up? im considering plugging a new 4017 in before i start desoldering anything

thanks again
 
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