![]() Failure to comply with either of these limits will cause both transistors to turn on at the same time, and they will fry. Likewise, when low, they MUST be less than about 0.5 volts. A and B, when high, MUST be greater than about 4.5 volts (one diode drop below 5 volts). When both inputs are either low or high, the voltage across the LEDs is zero. When A is low and B is high, Q2 and Q3 are on and Q1 and Q4 are off, turning LED 2 on. Simulate this circuit – Schematic created using CircuitLab Assuming that your coding is A high gives LED 1 on, B high gives LED 2 on, A and B low gives neither on, and A and B are never high at the same time, something like I suggest that what you want is called an H-bridge. The LED will replaced by an outbound signal. I just need to add a second transistor switch and create a voltage divider which I already know how to do. in another post which will take care of reaching up to the 5V. I need a suggested schematic mod or an IC to accomplish what I am looking for if anyone has any suggestions! Thanks! I cannot find a shcematic or IC to accomplish what I am looking for exactly.but maybe my search terms are incorrect? Looking this up with google only yield results for a "tri-state buffer" that has the output possibilities of 0V, 5V, and high-z. When I apply voltage only to Q5 (the top NPN), I only get 3.03V at the output. With this schematic, I can get my ~0V and ~2.5V fine, but I cannot get 5V. Here is the schematic I have simulated in LT Spice. I want to create a 3-step signal that can be ~0V, 2.5V, and ~5V.įor starters, I tried using two NPN transistors controlled by two 3.3V output pins from an MCU. Basically I am trying to make a 2-bit DAC that can interface to an external device via one signal wire.
0 Comments
Leave a Reply. |