Firstly, congratulations on producing a very clearly photographed and explained video with absolutely no verbal bloat. I instantly understood the circuit diagram without listening to your explanation and the design is very elegant. I was searching for an over voltage protection circuit for an Arduino based instrument that I am developing and I need to protect one of the analog pins from exceeding 5 volts. This circuit does not quite fit the bill as I need something that automatically resets itself when the voltage drops back under 5 volts. I intend to adapt your circuit to use a LM431 Adjustable Precision Zener Shunt Regulator in place of the MAC97A4 triac. So many thanks for publishing this circuit. I have subscribed.
Great video and explanations. Have looked at multiple overprotection approaches, and this is one of the most concise examples that I have seen. Plan on building it this weekend to experiment with, as part of a project that I am working on. Absolute shame that this video does not have more likes, and that you do not have more subs. I really enjoy your style in presentation, and your knowledge!
One note of caution: there are two distinct types of green led available. The older type was not very bright even at 20mA, but only had a forward voltage of about 2V at that current. The newer type is much brighter, but has a forward voltage drop around 3.5V at 20mA. If you're using a 2V green led, then you have 3V/370R = 8mA through the 150R and the led/220R. The gate of the MOSFET will be at around 3.8V, which should be fine for the IRL540 (Vt=2V max), but not all "logic-level" MOSFETS will turn on as hard with that gate voltage. If you're using a 3.5V green led, then you have about 1.5V/370R = 4mA through the 150R and the led/220R. The gate of the MOSFET will be at around 4.3V. Personally, I'd be tempted to use 330R for R1 (which then doesn't need a higher power rating) and 470R for R4/R3. A high brightness green led is plenty bright enough even with 2mA. The current through the triac when triggered would be more than 15mA, which is still above the maximum holding current of 10mA.
In that case you would set the potentiometer for the voltage you are interested in limiting. You’d need to alter some of the resistor values for higher voltages.
Couldn't one just use a zener diode to open a normally closed relay, and in that way cut the power to a circuit when the input reaches the limit of the zener?
Firstly, congratulations on producing a very clearly photographed and explained video with absolutely no verbal bloat. I instantly understood the circuit diagram without listening to your explanation and the design is very elegant. I was searching for an over voltage protection circuit for an Arduino based instrument that I am developing and I need to protect one of the analog pins from exceeding 5 volts. This circuit does not quite fit the bill as I need something that automatically resets itself when the voltage drops back under 5 volts. I intend to adapt your circuit to use a LM431 Adjustable Precision Zener Shunt Regulator in place of the MAC97A4 triac.
So many thanks for publishing this circuit. I have subscribed.
Great video and explanations. Have looked at multiple overprotection approaches, and this is one of the most concise examples that I have seen. Plan on building it this weekend to experiment with, as part of a project that I am working on.
Absolute shame that this video does not have more likes, and that you do not have more subs. I really enjoy your style in presentation, and your knowledge!
Thanks Joseph
One note of caution: there are two distinct types of green led available. The older type was not very bright even at 20mA, but only had a forward voltage of about 2V at that current. The newer type is much brighter, but has a forward voltage drop around 3.5V at 20mA.
If you're using a 2V green led, then you have 3V/370R = 8mA through the 150R and the led/220R. The gate of the MOSFET will be at around 3.8V, which should be fine for the IRL540 (Vt=2V max), but not all "logic-level" MOSFETS will turn on as hard with that gate voltage.
If you're using a 3.5V green led, then you have about 1.5V/370R = 4mA through the 150R and the led/220R. The gate of the MOSFET will be at around 4.3V.
Personally, I'd be tempted to use 330R for R1 (which then doesn't need a higher power rating) and 470R for R4/R3. A high brightness green led is plenty bright enough even with 2mA. The current through the triac when triggered would be more than 15mA, which is still above the maximum holding current of 10mA.
Great video!, What if i used mac97a6 ? It still work isn't it?
I believe it will work.
Great project
I want circuit for variabl power supply?
In that case you would set the potentiometer for the voltage you are interested in limiting. You’d need to alter some of the resistor values for higher voltages.
@@simoncarter568 thank you
Couldn't one just use a zener diode to open a normally closed relay, and in that way cut the power to a circuit when the input reaches the limit of the zener?
Unknown, I’d have to see the circuit you are proposing.
😉
Please don't say that voltage passes through a resistor.... voltage is the potential difference at the leads it does not flow.