This is my first post and I'm a NOOB at this. I understand the basics of how circuit components work but I have trouble putting it all together.

My project is: I need a circuit that evaluates the voltages on up to 5 separate wires (each either 0 or 12v). When any or all of the voltages changes from either high or low I need a timer to trigger for about a 1/2 second to ground a relay.

This project is for an automotive project so needs to be based off of 12v.
I will be using it to monitor shift solenoids on an automatic transmission, and activate a relay during a shift for a period of about 1/2 second.

any input would be greatly appreciated. Please dumb it down for me

 

Perhaps you could make a five input AND gate from ten discreet diodes and trigger a 555 with the output.

 

My project is: I need a circuit that evaluates the voltages on up to 5 separate wires (each either 0 or 12v). When any or all of the voltages changes from either high or low I need a timer to trigger for about a 1/2 second to ground a relay.

You need to tell us about how this is being inputed. Are there switches on the shifter already that you're tying into? Also you should look into a 555 timer that is setup to be a one shot (aka monostable mode)

http://www.electronics-tutorials.com/devices/555.htm

Further information about the inputs is key tho for us to help you get anywhere.

 

This is my first post and I'm a NOOB at this. I I need a circuit that evaluates the voltages on up to 5 separate wires (each either 0 or 12v). When any or all of the voltages changes from either high or low I need a timer to trigger for about a 1/2 second to ground a relay.

I'm just trying to ensure that I understand your situation correctly.

You need to have the capability of generating a 1/2 second "ground pulse" if any of your (up to five) input wires changes from 0V to 12V, or from 12V to 0V.

Is that correct?

 

OK...I have not bench tested this (and I don't have a simulator), but I think this might work. Each of the 5 input XOR's form an edge detector with a positive output pulse whos width is determined by the 100k resistor and the 4.7uF cap...about 1/2 second. The 5 diodes form a 5-input OR driving paralleled XOR's to drive the transistor that pulls the relay to ground. Don't know what the relay is, so no spec on the bias resistor or transistor. The 10K resistors on the inputs are to keep the XOR gate inputs from floating, if there is time when the input is not 0v or 12v as with a Break-before-Make mechanical switch...but not necessary otherwise.

Ken

OK... I bench tested one XOR input, and it performed as expected.

 

OK...I have not bench tested this (and I don't have a simulator), but I think this might work. Each of the 5 input XOR's form an edge detector with a positive output pulse whos width is determined by the 100k resistor and the 4.7uF cap...about 1/2 second. The 5 diodes form a 5-input OR driving paralleled XOR's to drive the transistor that pulls the relay to ground. Don't know what the relay is, so no spec on the bias resistor or transistor. The 10K resistors on the inputs are to keep the XOR gate inputs from floating, if there is time when the input is not 0v or 12v as with a Break-before-Make mechanical switch...but not necessary otherwise.

Ken

OK... I bench tested one XOR input, and it performed as expected.

An edge detection circuit is exactly what I need I just didn't know the terminology. And the 5 input OR gate would work also, I was thinking of using a timer on the output of the OR gate but I would like to be able to fine tune the on time of the relay. What would determine the bias resistor? the impedance of the relay coil?

I've been reading all of the technical manuals on this site for the last week and for the life of me I can't understand how alot of the circuits work. I understand the theory mostly, but when I look at the circuit it's like I'm trying to read chinese. I'm the kind of person that has to see it in action to understand.

 

Here is another, but untested, circuit. Maybe I can bench test it tonight. Note that the XOR gates have been changed to XNORs and the diode directions have changed. I think the relay On-time can be varied from about 0.2 Sec to 2 Sec.

Ken

Bench tested and works OK!
Still don't know anything about the relay so no spec's on R11/Q1. Relay coil resistance will determine how much current it uses, and point to the correct transistor and resistor.