To get 0.1V saturation voltage you usually need to run a very high base current. The power wasted in the base resistor can be substantial. There's also a lot of power being dumped into the base-emitter junction itself, which unlike the collector, will be greater than 1V when the transistor is in saturation. The base-emitter junction will be dissipating more power than the collector!Hmmm, I wouldn't define less than 0.1V drop for a BJT transistor in saturation as a lot. I've just bought a bunch of CMOS 556's too, so they're out there.
To get 0.1V saturation voltage you usually need to run a very high base current. The power wasted in the base resistor can be substantial. There's also a lot of power being dumped into the base-emitter junction itself, which unlike the collector, will be greater than 1V when the transistor is in saturation. The base-emitter junction will be dissipating more power than the collector!
To get 0.1V saturation voltage you usually need to run a very high base current. The power wasted in the base resistor can be substantial. There's also a lot of power being dumped into the base-emitter junction itself, which unlike the collector, will be greater than 1V when the transistor is in saturation. The base-emitter junction will be dissipating more power than the collector!
Blueteeth> Thank you for the information and I really appreciate it.
Other than V=IR, P=VI I do not know anything about electronics/electrical. I am just picking things up from the internet and trying my own DIY stuff. What the resistors and capacitors are doing in the circuit I have no idea. When you guys look at a circuit and do you already know exactly what each component's role is?
I have heard about the MOSFET heating up but as I will be using this LED Light for Scuba diving I guess heat can be dissipated easily through the torch body.
Thanks Blueteeth.
I had just received the Cmos 556 today and everything is working greatThe Mosfet is not as hot as i expected. Other users have feedbacked that the Mosfet was too hot to touch using a normal 556 and 7.2V.
Your website on the 555 is very informative, I bought a dedicated control circuit to toggle the current between high and low for the LED. But after reading about the timer I could use it to toggle between high and low. Seems like a very basic yet useful chip.
Many thanks
Cliff
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