I am trying to work out how many .6v drops across diodes to make a dummy load,cant see how many diodes i need,its a m -140 2 watt diode im trying to simulate to set the driver current,cheers m3-vuv.
You have to also bear in mind the voltage drop across the current shunt resistor you end up using. - so V=I*R for the current measurement and the measured shunt value (don't use the quoted value, measure the shunt yourself).
I think the datasheet operating range for the M140 is 3.7V-5.5V so anecdotally use 5-7 diodes
Check the datasheet for the diodes you're using in your dummy load too, voltage drop across a regular rectifier diode shifts with changes in current/temperature.