| Electronics > Beginners |
| Transistor Switching |
| << < (4/7) > >> |
| ruffy91:
Regulate current, not voltage. |
| tpowell1830:
--- Quote from: ruffy91 on July 08, 2018, 01:06:03 pm ---Regulate current, not voltage. --- End quote --- BINGO! Where do you put the resistor on a transistor hookup for current regulation? Keep in mind that you will need to regulate from approximately 50 µA (not 0) to 100 mA. Still, not the method that I would recommend. |
| Oslaw:
Thanks Everyone. I used a new 9v battery and it burnt the LED and got the transistor hot ( replacement LED also got burnt). It seems the dimming was probably a result of the LED glitching due to over-current.( New 9V Battery: 9.01 V and Old 9V Battery: 7.48 V ). |
| Zero999:
--- Quote from: tpowell1830 on July 08, 2018, 01:37:57 pm --- --- Quote from: ruffy91 on July 08, 2018, 01:06:03 pm ---Regulate current, not voltage. --- End quote --- BINGO! Where do you put the resistor on a transistor hookup for current regulation? Keep in mind that you will need to regulate from approximately 50 µA (not 0) to 100 mA. Still, not the method that I would recommend. --- End quote --- The resistor needs to go in the emitter side, to regulated the current, which can then be controlled by varying the base voltage with the potentiometer. Also what's wrong with regulating down to 0mA? And 100mA is too high for a small 5mm LED. |
| MK14:
--- Quote from: Oslaw on July 08, 2018, 04:06:05 pm ---Thanks Everyone. I used a new 9v battery and it burnt the LED and got the transistor hot ( replacement LED also got burnt). It seems the dimming was probably a result of the LED glitching due to over-current.( New 9V Battery: 9.01 V and Old 9V Battery: 7.48 V ). --- End quote --- You should be using/designing circuits, which respect the limits of the components. E.g. Transistor bases, LEDs and things, don't like big currents. Otherwise, you will risk breaking the components, which is what you seem to be saying, has just happened. I still haven't seen a proper schematic of how you wired things up, or an explanation of exactly what you are trying to achieve. So it is difficult to comment any further. |
| Navigation |
| Message Index |
| Next page |
| Previous page |