Backup mirror modification

[TDot]

Back to this now....
This looks very interesting, however 1: now were getting into creating entire circuit boards which would need to be mounted somewhere and preferably enclosed instead of inline wiring. 2: how long would the car need to stay in reverse in order to charge the thing up. 3: why is all of this circuitry needed over simply using a capacitor by itself or am I oversimplifying what I understand a capacitor is capable of doing (being that a capacitor is incapable of holding a charge to keep the switch grounded for 1 min or so)?

We're getting closer.

[svard75]

Did you watch the youtube vid I posted? I could still put this all together without a board just solder some insulated wires in between and tape it all up into two cylinder shapes with the wires leading to the main relay using flat connectors. The issue with installing this would be the wires required to connect to all the important points in the car. The drivers position system is under the drivers seat, the BCM is somewhere under the passengers dash.

[TDot]

Yes I did, but it didn't answer 2 or 3 for me unless I missed it. I'll watch it again. I'm glad you posted that, I've had the need of a time delay device in the past and could have used this. I guess a quick and dirty mash up can be made by wrapping everything up. I was never planning on getting to the BCM or DPS, I was going to do everything behind the switch harness. The only thing I don't like about this vs the button catch and release, is being subject to wait until the timer is up. Many scenarios of changing your mind in the parking space and then to have to wait for it to return can eventually get annoying. But it's still a plan to consider.

[svard75]

2. Time is calculated by multiplying Resistance of the circuit times the microfarads of the capacitor. In the case of this circuit the resistance is after the capacitor so assuming there is 0 resistance in the actual wires it would take 0 seconds to charge the capacitor up fully (time in seconds=Resistance x Capacitance). The reality is there is a slight resistance in the wires themselves but it should be fine within the 20ms pulse times.

3. You need some resistance in the circuitry so that the capacity retains it charge for some time. That's why in the vid the guy mentions if you play with the resistance you increase/decrease the time the capacitor stays charged up. If you used just a capacitor without anything else it would discharge in 0 seconds again. The diodes keep the current flowing in the one direction to charge the capacitor up quickly then the resistor on the other end allows for a slow discharge. Keep in mind that depending on the resistance of that resistor the discharge rate is calculated the same way. Also capacitors loose voltage as they discharge over time so this also needs to be kept in mind while designing the circuit. I think you may be able to find a relay that is a lower voltage such as 10v dc instead of 12v. It should still be fine if it's overvolted by 2 v. Perhaps there's tolerances for this IDK.