Hello, I would like to find the output voltage (peak) of the joule thief.
Using the schematic at http://rimstar.org/sdenergy/joule_thief/joule_thief_circuit_diagram_schematic.jpg I made one that works.
However, I cannot seem to find the output voltage. Using a DC regulated power supply and Tektronics oscilloscope how do I find the output (across the LED)
P.S. Please use simple terms :)
Quote from: CommanderJerome on January 15, 2015, 09:28:13 AM
Hello, I would like to find the output voltage (peak) of the joule thief.
Using the schematic at http://rimstar.org/sdenergy/joule_thief/joule_thief_circuit_diagram_schematic.jpg I made one that works.
However, I cannot seem to find the output voltage. Using a DC regulated power supply and Tektronics oscilloscope how do I find the output (across the LED)
P.S. Please use simple terms :)
Take a 2' length of two wires of different colors and twist them tightly together, at least four twists per inch.
Strip each wire at the same end.
Solder one of the just stripped ends to the LED anode and the other to the LED cathode.
Now strip 1" from each wire at the other free end.
Make a loop of the 1" free end and solder the loop closed.
Place the oscilloscope 1' to 2' away from the JT.
Lay out the twisted wire away from the JT towards the oscilloscope.
Now connect the oscilloscope probe ground clip to the loop on the wire that goes to the LED cathode.
Clip the oscilloscope probe to the loop on the wire that goes to the LED anode.
Set the oscilloscope to trigger on the rising edge waveform of the channel you just connected.
Adjust the oscillocope vertical settings so that the waveform fits on screen.
Adjust the trigger for the midpoint of the waveform.
Adjust the horizontal settings so that one to three complete cycles fit on the screen.
If the oscilloscope is a basic analog model, read the number of divisions from the bottom of the waveform to the top and mulitply by the vertical sensitivity.
If the scope has cursors you can use them.
If the scope has amplitude measurement functions you can use the peak to peak function.
led is not liner load but graph you see on scope one for volts one for amperes and referance points may help to calculate power graph.