ESP8266 Community Forum

- Fri Jun 07, 2019 3:46 pm #82733 It is hard to know what is the best method or device to use. It would be very helpful to be able to see what kind of pulses are riding on the battery voltage when the bike is in operation.

I would put a 1mH inductor in series with the input. That will give some separation, a reduction, of the energy the clamping device needs to handle. The value can be evaluated when running the board. This may not necessarily be the best approach, just one that I have used in the past.

I changed the schematic to what I would do. I would not try and clamp the power for the ignition coils. I would add a series inductor, then clamp the voltage for the regulator input as well as the driver chip.

Crude edit, but it is the best I can do.

A few years ago I designed the electronics for an electric motor driven sand and salt spreader. For sanding streets and parking lots in the winter. There was a conveyor motor and a spinner motor. The conveyor was a 3/4 hp motor. The rated running current was 55 amps at 12 volts. The electronics and firmware limited the starting current to about 120 Amps. The spinner motor was 1/3 hp. I the running current was about 30 Amps. The operator was able to set the speed of the spinner and conveyor with a Bluetooth app.

There was three mosfets for the spinner motor. Four (and another four for the reverse direction) on the conveyor. I used gate drivers like in the above design. I used 12 Ohm resistors in series with the gate of each mosfet.

The motors used created high power transients. I had three stages of filtering/clamping to deal with the transients. High power transorbs, resistor with series capacitor as a snubber circuit, and back emf diodes (big) across the motors. It was an interesting project.

- Fri Jun 07, 2019 4:36 pm #82734

A few years ago I designed the electronics for an electric motor driven sand and salt spreader. For sanding streets and parking lots in the winter. There was a conveyor motor and a spinner motor. The conveyor was a 3/4 hp motor. The rated running current was 55 amps at 12 volts. The electronics and firmware limited the starting current to about 120 Amps. The spinner motor was 1/3 hp. I the running current was about 30 Amps. The operator was able to set the speed of the spinner and conveyor with a Bluetooth app.

Interesting, kinda unexpected IoT device
I can't imagine the tracks width

Back to my circuit, the equivalent Circuit of DSS6NC52A471Q55B is



but why the only refered value is the capacitance even if there is two inductors ?

Should i keep this or put a single 1mH inductor ?

And if I keep the IRLZ44N I currently have, with max VDS of 55V, I think that it would cause problems so I should also change for the one I mentioned above.

BTW, I think that this is my final circuit.

- Fri Jun 07, 2019 9:15 pm #82735 Looking at your layout I will suggest one thing because you have space for them. The 555 based schematic you included had external diodes from source to drain. I know that most mosfets will have an internal diode but many are not optimum for use. They are often a parasitic element. Sometimes it is better to add an external diode that will either have a faster response, or a lower voltage drop. For whatever reason, they were included in the 555 design. If you don't need them, then you don't have to put them in. But if you don't include it, and later find that you need them, it would be harder to add them.

Also the diode in series with the coil. I expect that it's purpose is to protect the mosfet from the higher generated pulse on the primary side. (as opposed to the much higher voltage on the secondary) I did a quick search on the internet on 555 based circuits and found this. https://forum.allaboutcircuits.com/thre ... st-1339949

what are the voltages if it does make kickback spikes?

Depends on the coils winding ratio. The old 12V round coils had somewhere around 200V to 400V depending on the coil.

Other information without the diode addition lists some transistors with collector voltages higher than 200 volts. I have concerns that the parts you intend to use may not be up to the task. But there are other parts available in the same package and pinout, so you may need to change it, but there are lots of options.


The DSS6NC52A471Q55B filter is intended for higher frequencies that I am concerned with. It is a good device but it will not do much for 20 KHz frequencies. (just pulled that frequency out of a hat) It really would be good to see what kind of waveforms you have to deal with. Then a more informed decision could be made.

In the end, an inductor, will just limit the amount of work your surge suppressor has to deal with. Yes they are rated for a lot of watts, but not continuous, and with specific pulse widths. I have used them, and have had them blow. All I can add is that you may not have a nice 12 volt battery as a power source. It might have nasty sh*t on it that might be hard to deal with. And might be why the ESP12 module failed.

One more wrinkle. If there are 100+ voltage spikes on the supply, an inductor used as I have, will need to withstand that voltage end to end. Some compact inductors may not have the end to end isolation/separation.

- Mon Jun 17, 2019 6:18 pm #82850 Ok guys so I come back because I received the PCBs and components, made one working pcb and :

It worked fine (replaced the hall sensor with a switch just to test)

But then I wrote a program to simulate 10,000 rpm so with 6ms interval between sparks and, ECU fried

It worked fine during 5 seconds, even my main computer screens shut off then nothing