TT081/2 Hau LED current source

Simple pot-controlled 0-750mA current sink for an LED, based on ToprCS2Bridge:

Power supply is a 7.5V 1A wall wart.

Might get unstable for reactive loads, so I recommend using component values in TT081B.

We're seeing leakage through the MOSFET that's slightly turning on the LED.

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TT081B puts the D/A back onto the ToprCS2Bridge and connects it to a TipTop1590GRP

The Arduino code creates pulses at a programmable frequency from 10 Hz to 1 KHz, with a programmable on current from 0mA to 750mA

Here's the Arduino code.  The processor looks like an Arduino 'Raspberry Pi Pico"

Commands follow the standard lab protocol.   Connect through a virtual comm port, with TeraTerm, PuTTY, etc.

Typing "?" gets a list of available commands.

All commands to update parameters are a single capital letter, followed by the argument, followed by a semicolon.

If the command is acceptable, the Arduino replaces the semicolon with an exclamation point.  If not, with a question mark.

Commands to read current parameter settings are a single lower-case letter followed by a semicolon.

P<arg>; sets period of pulse in usec.  Arg range 1000 to 100000
p; returns period

O<arg>; sets on time of pulse in usec.  Arg range 1000 to 100000
p; returns period
C<arg>; sets LED current in mA.  Arg range 0 to 750
c; returns current
S; stores parameters into non-volatile memory

Screw terminal connectors are for the LED.  VTEC goes to the anode and OUTA goes to the cathode

There's also a BNC output with a TTL-level signal that is high when the LED is on.

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TT082 is a similar concept, but modified for a laser diode with a larger voltage drop