This is almost strictly a hardware question, and I'm double checking myself because I don't work with 24v much, so my test pieces are a bit expensive.
I'm using an Arduino to control 2 pneumatic solenoids with a fast response time. They are Festo 525150, and the datasheet can be found here. https://www.festo.com/us/en/a/525150/
they are 24V input, 3.7w, so they pull about 154mA.
My question is 2 part- Am I doing the math correctly on that transistor? Will it be able to handle the load? the fastest I will be switching is around 10ms.
the second part is about the base resistors- My code brings pins 12 and 13 high at a set interval- and when I run the circuit in the simulator, it only outputs around 6V. If I remove the resistors, it shows 24V. What am I doing wrong, or should I ignore the simulators and build it out on a breadboard?
If I'm barking up the wrong tree and there's a better option please let me know, Or if I'm on the right track.
Thanks!
The base resistors are necessary to limit the current out of the output pin. The recommended max current from an Uno pin is 20mA. Absolute maximum is 40mA.
What are the resistor values? The colors on the picture are not well defined, could be Red (2) or Orange (3), Black (0) or Violet (7), Brown (1) or Grey (EIGHT)?
groundFungus:
The base resistors are necessary to limit the current out of the output pin. The recommended max current from an Uno pin is 20mA. Absolute maximum is 40mA.
So using ohm's law with a 5v output from the arduino and 20mA, I should use a 250 ohm resistor, correct?
JCA34F:
What are the resistor values? The colors on the picture are not well defined, could be Red (2) or Orange (3), Black (0) or Violet (7), Brown (1) or Grey (EIGHT)?
If fast response is premium, then you shouldn't fully saturate the 2N2222.
Google "Baker clamp".
The diode will also increase turn-off time.
For high speed, look at mosfets and active clamping.
Leo..
Wawa:
If fast response is premium, then you shouldn't fully saturate the 2N2222.
Google "Baker clamp".
The diode will also increase turn-off time.
For high speed, look at mosfets and active clamping.
Leo..
JCA34F:
Drop to 220 (19.5mA) and if the on period is less than about 15 sec and duty cycle less than 40%, you might risk dropping to 180 (24mA).
@JCA34F- Thanks, I'll give it a shot. @Wawa- It's a priority but I don't think I'm anywhere near the speed for a Baker clamp- My absolute worst case scenario is 10ms. It'll be around 250ms for the most part. I looked at the data sheet for that transistor and mathematically it looks like it has a 3ms switching time. Please correct me if I'm wrong.
