This is the simulation on Falstad that works:
Where it is being done that way for tests purposes, but the objective is to use a TTL signal from the encoder to send a 24V signal to a PLC or Data Aquisition Board.
There are two transistors:
- A PNP (BC558)
- And a NPN (BC337)
The moment when the 24V source is turned on and the 5V switch is off, the LED lights on. Is it a problem from the transistor specs? Or It is to work that way and another thing is wrong...
Is it possible to make a TTL encoder signal conversion to 24V just with two transistors?
It worked with an optocoupler:
However, when testing with an encoder for the 5V input, the optocoupler couldn't switch on the required frequency. So a new NPN transistor was used and the circuit worked:
And the PLC read the encoder pulses correctly.
So I got rid of the 24V at the base of PNP. It is working, however, any noise on the circuit can make it send pulses incorrectly.