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I believe this one is right.
Originally Posted by Beefy /img/forum/go_quote.gif Alright, back from Xmas shopping, how about this then? Gate is now positive to source by a variable - and measurable - amount. |
Originally Posted by digger945 /img/forum/go_quote.gif Whatever your Idss measurement is(from your first test), then that is going to be about the lowest current measurement your going to get(with the gate and source shorted together). For example, if you have one with a Idss of say 11mA, then as you lower the Vgs from a point where both gate and source are the same to something where the gate is seeing less potential than the source, then the current is only going to increase. |
Originally Posted by runeight /img/forum/go_quote.gif You got a 12V zener? |
Originally Posted by digger945 /img/forum/go_quote.gif The 271 is not a transistor, it is a depletion mode fet. |
For the P-channel, as the gate voltage increases with respect to the source, the flow of current decreases. |
Perhaps this will help. |
I haven't done the math. |
Originally Posted by sumo-kun /img/forum/go_quote.gif Just a quick question about power transformers. What is the recommended secondary voltage spec for the hybrid? On site, it mentions 240VCT on the scematic but the BOM says to get a 250VCT. I remember a load of discussion a while back in the thread about the Hammond 270xxx and 269xxx and which one works/doesn't work but I can't remember. I seem to recall the 270 was supposedly too low in the current rating but it worked fine in practice and the 269 produced overheat problems, which resulted in the need for a 300V zener string instead of the 291? I will probably be getting a transformer locally because the voltage over here is 100V/50Hz. I found a candidate but I just want to make sure its OK. Its a 240VCT 100mA. Over specced in the current department but is the 240V OK? It also has 3 6.3V/2A taps. Is the 2A rating enough to run both heaters off of it? |
Originally Posted by runeight /img/forum/go_quote.gif Well, as it turns out, splitting the panel will only add cost. At this point I will just get both amps and assume that they all will go out. |