Hi poynt, Rose, Havery, Aaron, Glen et ALL.
Still fine tuning guys got a better results then last time, got a few tests done, looking forward to the new data Glen, Harvey this is a great help my friend. Okay here is the message i got back From Andrew
Hey all,I have replaced the capacitor and resistor values from the August 12 2009 revision to the newer August 26 2009 revision and having better luck.
Notes and observations:
resonant / optimal frequency of inductor operation (max spike power going into cap / 470 ohm resistor): 960KHz, 55% (meter indication only).
I added a grey rubber Mosfet insulator between the mosfet and the heatsink, with white heat transfer grease. I still get wild oscillations if the series gate resistance isn't correct. Could it be that the series variable 10 turn resistor would be acting as an antenna also?
Input power: 24.1V 1A (output of pi filter - capacitor -> inductor -> capacitor)
The 555 timer warmed up significantly greater than the ambient temperature. Maybe we should replace the 1nF capacitor with a 0.1nF, and the resistors with 10x their resistance value? That would achieve the same frequency and duty cycle using less power. I had 13.8V going in to the 12v regulator (7812) and the regulator was also warm. It might be worth looking into a frequency generator using more modern components with sharper square wave forms?
Temperatures:
Ambient - 29C / 84F
10 ohm resistor - 64C / 148F
555 chip - 54C / 129F
IRFPG50 Mosfet - 50C / 122F
The capacitor, diode and resistor combination are the same for collecting the spikes off the resistor: 4700uF / 50V, 1N4007 diode, 470 ohm resistor. 4 volts was measured across the 470 ohm resistor which was across the 4700uF capacitor.
I calculated the inductance of the 10 ohm resistor, using the coil calculator link Harvey mentioned (www.66pacific.com/calculators/coil_calc.aspx). Our resistor has 23 turns, 1" diameter, 4.5" long = 2.7uH. A photo of the resistor we purchased is at http://img-asia.electrocomponents.co...F252618-01.jpg
Thoughts or comments anyone?
Andrew
Still fine tuning guys got a better results then last time, got a few tests done, looking forward to the new data Glen, Harvey this is a great help my friend. Okay here is the message i got back From Andrew
Hey all,I have replaced the capacitor and resistor values from the August 12 2009 revision to the newer August 26 2009 revision and having better luck.
Notes and observations:
resonant / optimal frequency of inductor operation (max spike power going into cap / 470 ohm resistor): 960KHz, 55% (meter indication only).
I added a grey rubber Mosfet insulator between the mosfet and the heatsink, with white heat transfer grease. I still get wild oscillations if the series gate resistance isn't correct. Could it be that the series variable 10 turn resistor would be acting as an antenna also?
Input power: 24.1V 1A (output of pi filter - capacitor -> inductor -> capacitor)
The 555 timer warmed up significantly greater than the ambient temperature. Maybe we should replace the 1nF capacitor with a 0.1nF, and the resistors with 10x their resistance value? That would achieve the same frequency and duty cycle using less power. I had 13.8V going in to the 12v regulator (7812) and the regulator was also warm. It might be worth looking into a frequency generator using more modern components with sharper square wave forms?
Temperatures:
Ambient - 29C / 84F
10 ohm resistor - 64C / 148F
555 chip - 54C / 129F
IRFPG50 Mosfet - 50C / 122F
The capacitor, diode and resistor combination are the same for collecting the spikes off the resistor: 4700uF / 50V, 1N4007 diode, 470 ohm resistor. 4 volts was measured across the 470 ohm resistor which was across the 4700uF capacitor.
I calculated the inductance of the 10 ohm resistor, using the coil calculator link Harvey mentioned (www.66pacific.com/calculators/coil_calc.aspx). Our resistor has 23 turns, 1" diameter, 4.5" long = 2.7uH. A photo of the resistor we purchased is at http://img-asia.electrocomponents.co...F252618-01.jpg
Thoughts or comments anyone?
Andrew
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