Project Description
Main Project Image
The project owner hasn't added main project image yet.
Project description
Note, the component values were what I had ready at hand, not optimized for anything but expedience! :)
Control signal input can be driven by any uC's GPIO, I used an Arduino for all the usual reasons. In the absence of an input, Q2 does not conduct, so R2 pulls Q1's gate high, and because it's P-channel, it doesn't conduct either. In this state, crank voltage (typically 6-7 volts) flows through D2 to the DUT.
Drive the control signal high to turn on Q2, which pulls Q1's gate low, and run voltage (typically 13-14 volts) flows through D1. D2 becomes reverse-biased and no longer conducts, so the DUT is powered exclusively by run voltage.
Bypass SW1 allows the DUT to be manually forced onto the run supply, averting the next scheduled crank dip while the operator works on the DUT.
An LED on Q2's base might be nice to add.
Gallery
The project owner hasn't added any images yet.
Design Files
Embed Code
Component (7)
Qty
Description
SPST Toggle
SW1
1
Generic General Switch
Resistor
R1
1
Generic Resistor (100)
2n3904
Q2
1
Generic BJT (NPN)
1n5822
D2
1
Generic Schottky Diode