Electronic Circuit Breaker - Final & Some Future Projects

Nice job on the circuit breaker build Tony!

You didn't show your rotary switch for the cycle counts. If you turned it to 16 counts will the surge current still trip Thanks

I just noticed you have a RC filter across the output doesn't that draw current and show current draw on your meter with no load on the output??

All work and no play makes for a tired exhausted Tony.
Looking forward to the upcoming projects
Thanks for sharing
👍 👍 👍

If a mosfet was triggered by noise of touching terminals with a screwdriver, the drive circuit wasn’t designed properly. The sensitive gate SCR is just hiding an inherent instability.

Good to see you, I look forward to your channel. Thanks 🙏

Hello,
It was interesting video. Why did you add delay capacitor instead using the cd4040 counting for the delay?

That is pretty neat. I have been building a Test jig for testing equipment. I might see about adding the circuit breaker to it. Would those Stop Light Bulbs work as a Dim Bulb? It's starting to get harder and harder to find incandescent bulbs in my area.

Nice project, but personally it would bother me that the volt/amp display is not always on from the moment you set the mainswitch of the circuit breaker on.
You can achieve this by connecting the powerleads to the volt/amp display right behind the mainswitch, and before the protection part of the circuit breaker.
The testleads from the volt/amp display can leaved on the output of the circuit breaker like they are connected now.

Great project and thanks for sharing it. I was thinking to use an SSR to be driven by 4040 as opposed to all these SCRs. Your thoughts?

Works very well. Looks like a good project.

You should put a link to a schematic in the description. Thanks for your video!

very interesting

Close this annoying text bar

The circuit is fantastic but I wish I could say the same for the enclosure, reminds me of the lyrics to a song " Nice legs, shame about the face"... It's form factor might mean that you couldn't put anything on top of it, work spaces are tight enough as it is LoL.

How about a link to a schematic we can see. What SCR's did you use?

I'd use a GFCI Outlet , rather than ALL of this circuitry!

I asked this in a comment to the previous video and got no answer... Shouldn't you rewire that multi-drop switch to different outputs of the decoder chip, since you're counting half-cycles, not cycles? When you set you selector to 32, your device will trip after 16 cycles.

Enjoyed this project Tony! Thanks!

Interesting variation on Ron's design but can you explain why you added the "slow start" circuit rather than just setting the cycle count (4040) to a larger number say 32 or 64, I thought the purpose of cycle counting was to delay the cut-off for loads with a high inrush current?

Did you get my email?

Love your videos

Great video Tony. I noticed that the ground clip of one of the oscilloscope probes was clipped to itself. Is that to make sure that the two probes are both referencing ground?

Looking at that circuit, to work on + and - cycles the current coil must be sat at 2.5V DC. Also that display is unfortunately no longer available so another solution would probably have to be found. Ron's idea of using a transformer is a good alternative solution. The signal could also be rectified then referenced to ground or the 2.5V as in your circuit

Hi, Where did you get that current reference from?

Damn useful circuit - esp. the analysis and demonstration of its operations are valuable to experimenters who wan to tinker with faulty equipment. Ideally, I'd really like the meter to stay on after the circuit breaker trips and to continue showing the tripping current and voltage values. Maybe there's a meter out there that has a hold function.
I don't know if this circuit would be suitable for this type of usage but I'd sure like to have something like this to function as a loudspeaker protection device. This would be useful for certain modern extremely spartan amps. that do not feature speaker protection. In the '70's and '80's there was no amp without one but a lot of expensive amps nowadays come without.
Or - again with the same caveat as above - I'd like to have something like this acting as a mains current monitor used to protect sensitive equipment further down.

Thanks for picking this up from GlassSlinger and making your useful mods. I particularly like the Thyristor arrangement to replace the relay and the use of a window comparator to catch either half of the wave. That addition can be very helpful for the old sets that used a "hot" half wave diode for the B+, like a 35W4. When it shorts it can be on the other half of the wave from the positive.
Also I liked your 15 position current set switch idea which I would then series with a "fine" adjust pot. Just like on other test gear it would allow for a "calibrated" current when set to zero fine and then give you adjustment up to the next step as you add resistance. I definitely will build this because I was already in the middle of redoing my current dim bulb, variac, and isolation transformer system to include leakage testing and ground failures like the old Sencore testers did.
This will be a great finish to the project. One other thing though, just as with the meter display I intend to have a separate power lead that feeds just the electronics and keeps the "mains loop" separate. That will allow the breaker to work in circuit after the line variac. Keep up the good videos, really enjoying them.

Nice design, I will make one similar.

Nice .. I even thought of using a motor starter/contactor for the load interrupt (with your electronic drive) ...

Of course I was due to see this eventually. Anyone is free to make modifications to the concept. That does NOT guarantee that the new circuit is well tested over time (20 years) or even short term with various shorts. This fellow and his circuit has overlooked certain problems that may manifest under certain types of load short that will not happen with a relay circuit. I stand by my tried and tested (over 30 years) circuit.

Hello Tony, could you please share PCB and schematics files? Thank you!

Hello, i came across your channel couple of days ago and i like stuff you post. I'm as well repairing/refurbishing vintage hifi stuff so i was happy to see lots of content i'm interested in. Some time ago i was thinking about some kind of circuit breaker in addition to good old light bulb so this really came in handy. I saw in replies that you said circuit in video got some revisions so is it possible to get latest schematic(if there is any?), gerber/pcb files are not important cause i can design it easily and i'm happy to share it.

I saw first the original video and thought, hmm I should build one of those one day. Today I’m aligning an old radio and accidentally touched the chassis to the radio ground; tripped the area breaker. That does it! I’m building this! 😆

Xraytonyb Mr., different equipment surge pulse number is different, should be how to set the counter gear, and how to ensure that can most quickly cut off the short-circuit current?

@TonyB You have encouraged us to design the circuit to meet our needs. That challenge includes, somewhat, building the unit with the components that we have on hand, as you did. Typically, I like analog solutions, instead of throwing an Arduino at every circuit. But, maybe I can solve this design better, with a digital approach. Off the top of my head and out of my component stocks... An ACS724 Hall Effect Current Sensor reads the Mains current draw and feeds that information to a small MCU (maybe an ATtiny85, if it will suffice. It depends on what ADCs and DACs are needed.) A Crydom D1225 SSR controls the mains (Its control input can be driven directly by the MCU, say 5V at 7uA, IIRC. The Amperage Trip Point Value, Cycle Counting/Delay and In-Rush Tolerance can all be managed in software, I think. I am not so much of a digital guy, so does that sound like it might work? What dragons lie in wait? All help welcome.

Hi Tony, it's an older video, but it still won't work for me (I have something similar at my workplace, the maximum current can be set directly in the meter, and when it is exceeded it can trigger an optical or acoustic alarm, or turn off the circuit), I remembered this video because I am solving an adjustable electronic fuse for another test device. When I was watching the totofinal video, I thought of the display of the set level of the tripping current. I don't have it verified, it's just an idea, if tandem potentiometers were used for fine and coarse settings - track1 for current setting and track2 for voltage divider for the small Voltmeter on the panel, then it could be calibrated so that the voltage value on the Voltmeter corresponds to the set tripping current. I'll probably try to test it when I have time, unfortunately I have a lot of other work to do.

Nice day 🙂 Tom