Hi All,
I wonder if somebody can help me see where i've gone wrong.
I've followed a few guides on the web as to make a 555 LED "Throb" and this is what i've got so far.
BC141-10 - Low Power LF NPN Transistor in TO39 Case
555 Timer
100v 100 uF
33K Resistor
Pin 1 - Ground
Pin 2 - Connected to pin 6 & Base of BC141-10 NPN
Pin 3 - 33K Resistor to base of NPN
Pin 4 - Connected to pin 8 and 9V +
Pin 5 - Not in use
Pin 6 - Connected to pin 2 & Base of BC141-10 NPN
Pin 7 - Not in use
Pin 8 - Connected to pin 4 and 9V +
100v 100uF connected + to base of NPN and - to negative rail.
LED + from Emitter of NPN, and - from the negative rail.
With no load on I can see 2v - 5v ramping up and down on my multimeter, but when a load is connected the voltage stays constant, for example with a blue led it stays on 3.3V, and a yellow led 3v.
It fades up when turned on but then just holds.
Can anybody suggest any ideas? I've used the bigger NPN as I wanted it to be capable of "throbbing" 10 Yellow LED's.
I know not all the guides say to connect pin 2, to the base of the NPN as well, but without doing so I just get a constant voltage of 8V at the emitter of the NPN.
Thanks very much.
I wonder if somebody can help me see where i've gone wrong.
I've followed a few guides on the web as to make a 555 LED "Throb" and this is what i've got so far.
BC141-10 - Low Power LF NPN Transistor in TO39 Case
555 Timer
100v 100 uF
33K Resistor
Pin 1 - Ground
Pin 2 - Connected to pin 6 & Base of BC141-10 NPN
Pin 3 - 33K Resistor to base of NPN
Pin 4 - Connected to pin 8 and 9V +
Pin 5 - Not in use
Pin 6 - Connected to pin 2 & Base of BC141-10 NPN
Pin 7 - Not in use
Pin 8 - Connected to pin 4 and 9V +
100v 100uF connected + to base of NPN and - to negative rail.
LED + from Emitter of NPN, and - from the negative rail.
With no load on I can see 2v - 5v ramping up and down on my multimeter, but when a load is connected the voltage stays constant, for example with a blue led it stays on 3.3V, and a yellow led 3v.
It fades up when turned on but then just holds.
Can anybody suggest any ideas? I've used the bigger NPN as I wanted it to be capable of "throbbing" 10 Yellow LED's.
I know not all the guides say to connect pin 2, to the base of the NPN as well, but without doing so I just get a constant voltage of 8V at the emitter of the NPN.
Thanks very much.
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