Hi Guys
Can you help a wet behind the ears newby please?
I have a 5v microprocessor (ATMega328) based circuit that is being used to control various combinations of leds that are supplied with 12v. One of the microprocessor pins (pin B in sketch) presents a pwm signal to the base of an NPN transistor and also the base of a pnp transistor to reciprocally fade two leds up and down. All works well, but I now need to add a switch controlled by pin A to isolate that part of the circuit so both leds can be fully off at the same time. Refering to the sketch attached, will the addition of the npn and pnp transistors inside the dotted area achieve the switching I need do you think?
Also, I'm going to have to switch a second circuit using a further digital pin. The second circuit is basically a 556 based led flasher circuit driving no more than 250mA worth of led current. Could I simply sink this current with a single npn (2N2222) or do I need to source it with a similar setup as mentioned above?
If I need to source it, can anyone suggest a transistor array with both npn and pnp suitable transistors?
Sorry 'bout a)sketch quality and b)my naivety!!
Can you help a wet behind the ears newby please?
I have a 5v microprocessor (ATMega328) based circuit that is being used to control various combinations of leds that are supplied with 12v. One of the microprocessor pins (pin B in sketch) presents a pwm signal to the base of an NPN transistor and also the base of a pnp transistor to reciprocally fade two leds up and down. All works well, but I now need to add a switch controlled by pin A to isolate that part of the circuit so both leds can be fully off at the same time. Refering to the sketch attached, will the addition of the npn and pnp transistors inside the dotted area achieve the switching I need do you think?
Also, I'm going to have to switch a second circuit using a further digital pin. The second circuit is basically a 556 based led flasher circuit driving no more than 250mA worth of led current. Could I simply sink this current with a single npn (2N2222) or do I need to source it with a similar setup as mentioned above?
If I need to source it, can anyone suggest a transistor array with both npn and pnp suitable transistors?
Sorry 'bout a)sketch quality and b)my naivety!!
Attachments
-
33.5 KB Views: 62