Electric OU: MOSFETs….. How Do THEY Work? Offset Triangle Ramp Remix
This video illustrates the effect of Function Generator Offset setting applied to the Gate on the behaviour of an IRFPG50 power MOSFET. IMPORTANT NOTICE: The scope probe waveform trace shown in this video is not accurate; the probe was malfunctioning. The details and conclusions of the video aren’t affected by this, but the purists might have noticed that the “drain” trace didn’t look as it should. So I’ve fixed the probe (hopefully) and shot another video showing the proper shape of the mosfet drain trace. Sorry about that– and thanks for watching!
ERRATA:
1. The bulb used is actually a #161, not a #157 as I stated in the video. It is rated at 14 V, 2.7 Watts.
2. The shapes of the Drain Trace are not correct due to a probe malfunction. Please see the next video for the correct Drain waveforms.
The PG50 is going to be “ON” whenever the gate drive signal is over about +4 volts. By using the Function Generator’s offset knob, turned to a positive setting, it is easy to make _any_ drive waveform exceed the MOSFET’s gate threshold voltage for 100 percent of the time.
Rosemary Ainslie has recently published a set of photographs on PESN showing her claimed “overunity” apparatus using IRFPG50 MOSFETs. Her Function Generator is clearly seen to be set to produce a Triangle Ramp waveform at slightly over 1 kHz, with the Amplitude knob set to about 3/4 full and the Offset knob cranked all the way to the maximum positive offset. I believe this will keep the single Q1 mosfet ON for 100 percent of the time, just as I have demonstrated in this video. This is why Ainslie’s mosfet is on a large heat sink and why she can only show it working in this mode with 48 volts or less input, not the 72 volts she has claimed.
Materials used:
IRFPG50 power mosfet
#161 automotive bulb
Interstate F43 Function Generator
Tektronix 2213a Oscilloscope
Elenco Precision Dual PSU
A great big sweet Little Pickle