Hello.
I came up with this based on what was said on HEF.
What I came up with is a very simple circuit based on a "hidden switch", but in plain sight.
This is nothing more than a reed switch (a switch that operates in the presence of a magnetic field) and an SCR, (a solid state switch), and a keychain magnet.
You place your key in the ignition like you normally do and turn it on.
The magnet only needs to be near the reed switch to operate so if it is mounted near the keyswitch it will operate from the keyring magnet.
The SCR acts as a "latch" preventing the circuit from cutting out as the magnet moves about.
And, again, the reed switch could be mounted almost anywhere.
Once triggered, it stays on until you turn the ignition off for anywhere from instant to several minutes, your choice.
Keychain magnets are cheap and the circuit itself is under $5 complete.
The circuit itself is a reed switch rated at 200 mA, a generic SCR rated at 7 or more and 50 volts or more, a 50 to 2300 uF electrolytic cap, a diode rated at over 1/2 amp or more and 50 volts or more and a resistor rated from 1 to 22k.
The cap and resistor are how you select time delay, anywhere from 1/30th of a second to around 150 seconds is a valid value.
I can provide a schematic if need be, but with only 5 parts there is very little to it.
I came up with this based on what was said on HEF.
What I came up with is a very simple circuit based on a "hidden switch", but in plain sight.
This is nothing more than a reed switch (a switch that operates in the presence of a magnetic field) and an SCR, (a solid state switch), and a keychain magnet.
You place your key in the ignition like you normally do and turn it on.
The magnet only needs to be near the reed switch to operate so if it is mounted near the keyswitch it will operate from the keyring magnet.
The SCR acts as a "latch" preventing the circuit from cutting out as the magnet moves about.
And, again, the reed switch could be mounted almost anywhere.
Once triggered, it stays on until you turn the ignition off for anywhere from instant to several minutes, your choice.
Keychain magnets are cheap and the circuit itself is under $5 complete.
The circuit itself is a reed switch rated at 200 mA, a generic SCR rated at 7 or more and 50 volts or more, a 50 to 2300 uF electrolytic cap, a diode rated at over 1/2 amp or more and 50 volts or more and a resistor rated from 1 to 22k.
The cap and resistor are how you select time delay, anywhere from 1/30th of a second to around 150 seconds is a valid value.
I can provide a schematic if need be, but with only 5 parts there is very little to it.