Hi all,
Back with more exciting
Flux Deluxe TVS Diode Updates. ![Wave :wave: :wave:](/i/s/wave.gif)
Today's Special: 24V TVS Diode Oscilloscope Graphs!
Good news, folks - the higher voltage TVS diodes look like winners so far! To save time I didn't circle stuff in the graphs below as I did yesterday before, so I'll narrate.
BTW, today's observations are brought to you by yesterday's blown parts. It's easier to find stuff if you know what you're looking for.
As with yesterday's graphs, the yellow line shows the "system" voltage as measured at the capacitor tank. It can run much higher than 40V. As I showed yesterday, when left unprotected it can go as high as 100V or more! The heater uses capacitors rated to 630V, so high voltage here isn't a problem, per se.
The purple line is showing the voltage on one heater MOSFET Source pin, and this is where high voltage becomes a problem. The pin has a max of 40V, as previously discussed.
This is the initial power surge from turning on the On/Off switch, which I did not consider until the heater forced me to.
Look at the line in yellow, which has a max of 20.8V:
The TVS diodes I opened with yesterday became active in the circuit at 18V or so - too low and restrictive a value for real world conditions.
The diodes I am using in the graphs below have an activation voltage of 24V, which I believe is around the sweet spot. I want to keep them
inactive and out of the circuit until they are truly necessary, which is when the magnetic field collapses following the release of the tactile switch. I have a few others TVS values coming today and tomorrow, so the final choice may be a few volts higher than the one used in the results below. These are working quite well, however, so they may yet get the gig.
These final two graphs show the same 15mm FD as yesterday with just a
single of these 24V TVS diode installed in the heater:
The purple MOSFET Source pin voltage is a very ho-hum 27.2V (in purple), which is great! That's WELL within spec.
Finally, the graph below shows a heating event in which the Flux Deluxe was charging a set of Sony VTC-5D batteries
while also plugged into a 10A mains power supply -
not recommended and not supported at this time. But it handled the situation just fine:
I am going to continue to test this solution in a variety of situations to see if I can break it, but I am very encouraged so far.
And that's your midday Fluxer TVS Diode Report. I'll probably be back again later with another update.
Cheers,