(noob to this forum… apologize for hand-drawn schematics… )
Ive got a project working to synchronize high power LED strobe to a motor, with the help of a Hall sensor sampled by the Arduino. Both the motor and the LED bank are driven via IRF520 MOSFETs whose gates are directly driven by digital outputs. Works nicely BUT… Cannot get sufficient power from the LED, and wondering where my bottleneck might be. Here are some details on the LED side of the circuit:
- LED bank consists of 12 parallel connected 10W COB LEDs (each one rated at 12V 0.8A)
- Code activates an LED flash of 1.5 milliseconds, once per revolution, or at about 15Hz
- The LEDs do flash brightly; but not enough. To check the pulse current, I connected an 0.1 Ohm resistor in series with the IRF520 and read it’s voltage with scope. The pulses read about 0.43Volts, meaning 3 Amps, for about 1.5 msec
- …However - NOT 10 Amps, which is the current draw I was expecting from 12 LEDs connected in parallel.
- Tried to improve it by increasing VCC (whilst also increasing the series resistor on the Nano’s Vin pin to protect it), all the way up to 19 Volts. But, this increased the pulses from 0.3V to only around 0.5V, so only 5Amps.
Cable leading up to the LEDs is relatively thick and about 1 meter long. Placing a 2000uF cap across the power supply didnt help.
Any ideas… ? ? ?