MisterBill2
- Joined Jan 23, 2018
- 18,566
That circuit in post #13 has the bases tied to each other and also the collectors. So if the transistors have any leakage current at all they will quickly both be biased into full conduction. That will indeed cause problems.Please explain how you feel this will result in self destruction. I see a high input turning on the lower transistor while holding the upper transistor off, causing a low at the output. The next scenario, a low at the input will turn the upper transistor on and turn the lower transistor off, causing a high at the output. Am I wrong? If so - I can take criticism. If I learn from my mistakes - I learn something. And I certainly don't purport to know "everything". In fact, there is more I don't know than what I DO know.
In a thread I posted recently I used the opposite setup with an emitter follower that worked. Unfortunately in my circuit, the device the buffer was powering has an internal short, causing excessive amounts of current to be drawn, which resulted in the destruction of a PNP transistor. Not being the most "highly skilled" person on this website, I make mistakes. Sometimes I give bad advice. When I learn it I amend my comments - or remove them altogether. So if you can teach me something then please - by all means, teach away.
If one is concerned about the circuit self destructing - then just use a CD4049 buffer. They can give either a high or low output, which can toggle the LED's as the thread starter is seeking to do. Only, with a 4049, there are six in a package and only one would be needed - provided (and I don't know this) they can handle the current for the LED's.
And we do not yet have any information about the power source. But we do now understand the application, which is for a quite bright set of lights that are easy to see while backing up a truck to a loading dock. The motivation for a hidden magnetic triger is not clear, though.
So we need more information from the TS to avoid random guessing