![]() If the Teensy datasheet has an output current plot, great use whatever it says for the output voltage at 10 mA sourcing. For a 10 mA load current, let's assume a 3.0 V output. The Teensy output goes to 3.3 V, but not at any significant load current. Here is one way to determine how to bias a bipolar transistor driver. My electronics knowledge is rudimentary, so the formulae I'm seeing online to calculate the bias are over my head. This leads me to believe my transistors aren't switching on completely, which I'm speculating is a transistor bias issue. If I replace the lamps with LEDs the LEDs light correctly. Hooking up my old Radio Shack multimeter indicates that the transistors are sending almost the full 3 volts to the lamps. I have those pins going to NPN 2N 3904 transistors to drive the lamps via 1.5K ohm resistors. ![]() The chaser in the Teensy is sending pins 16-19 HIGH in sequence. ![]() I upgraded the blue lights on the pack using the Teensy to drive a column of LEDs, so now I want to drive the red lights to streamline things. The pack currently uses a very old analog chaser circuit from one of the Forrest Mims books, but it's getting a little flakey. This is for a Proton Pack I built in 1984. I'm attempting to drive a series of four 2.5 V incandescent flashlight bulbs using a chaser sketch running on a Teensy 3.1 Arduino. Relays can switch currents far beyond 10A.This is my first post on this forum please let me know if I'm in the wrong place. If more power is required, you can also use the transistor to switch a relay. For inductive load (coil, relay) please think of the freewheeling diode. So, if you know the current flowing through the transistor, then you just measure the voltage that drops on the C-E path (collector-emitter) and multiply it by the current to get the power dissipation. let a current of 800mA flow and the power loss must not exceed 500mW. But here you have to pay attention to the limits. ![]() In the name you certainly meant the 2N2222, a bipolar NPN transistor. A calculation of the current flow is not required in this type of wiring, since it is negligibly small. Since you want to operate the transistor as a switch, you can use the circuit you linked. If you would drive the LED with 10 mA, a transistor needs about 100μA depending on the wiring. The current required by a transistor control is much lower (factor 200 - 1000) than the driving of an LED. Of course you thought wise and gentle on materials. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |