Figured I would post this here. I was thinking about our BLDC motors and thought maybe I should wire up a circuit to demonstrate the 6 step commutation sequence of a BLDC motor. Doing this with a microcontroller is really easy, so I thought make this a bit more difficult and have a little fun while doing it. I wired up a 555 timer in astable mode and output a really slow clock. Feed the clock into a synchronous counter and start counting clock edges. From there output into a decoder and decode the count into 6 separate signals, from signal 4 (should actually be 5, but timing issues...) send signal to the counter to load the default bit pattern of all 0s to reset the count. Back to the decoder, since the decoder is active low, you have to invert the outputs and then feed those into OR gates for the commutation sequence. The outputs form the OR gates drive the gates of mosfets, this isn't needed, but I figured since I was representing BLDC motor, might as well use mosfets, lol.

This is the actual commutation sequence:
AH + BL
AH + CL
BH + CL
BH + AL
CH + AL
CH + BL

I have this wired up with a 6 LED array. Yellow LEDs represent high signal, and red LED for low. Depending on the resistors chosen for the 555 timer, you can slow down the pattern enough to see the sequence.

And for anyone interested in trying this out, here is the schematic. I have this working on my bench right now, so the schematic should be good. I may do a video on this and compare to how much easier it is to do with a microcontroller...

Old skool electronics. On a Dutch tech forum most people only know programable electronis, people would even use an Arduino to make a LED blink. I would use a CD4017 with some diodes to make the sequence.

In the past I had the idea to make such a setup but then with an analog or PWM control to look up the sensor switching point as a timing measurement.

DIY Brushless Motor Controller Options - Pro's & Cons

I think using a CD4017 would greatly simplify my circuit, lol. But I don't actually have any laying around, I do however have plenty of other logic ICs. Maybe I will put a couple in my cart the next time I put in a component order.

I had half a mind to build out the timer function using using rc filters and comparators, but decided against that and just went with the 555. But with the CD4017, I think you can get rid of the 163, 138, and the 04. Hmm... I do like the idea, the question is whether or not I want to expend anymore energy on this build, especially since the next step it to put it on a microcontroller as the end goal is to build a motor controller.

Anyway, here is a revised schematic. I didn't add the 5V rail and missed a ground somewhere. Also put the load on the wrong output. That is what you get when you build the schematic off your circuit, lol.

EDIT: This is not a motor controller, this is simply a circuit built using digital ICs, mosfets, and LEDs to represent 6 step commutation.

That is no stepper control.....

But yes, I think there is a huge market for a stand alone brushless driver to convert nitro starter boxes to brushless

Huge market you say... What size motor and ratings? I am guessing pretty beefy, I wonder if an ESK8T ESC would work?

Ah, you also changed the counter reset, that is making more sense now.
To simplify the schematic more, use an ULN2003 for the LED's

Most starterboxes are powered with 2 simple 540 motors in series powered by a 12v PB battery, 12S NiMh (2x stickpack) or most common today: a 4S LiPo. The Hudy starterbox is powered with one 775 motor.

I think a single 540 size brushless 13.5t or 17.5t has enough power to start engines from a 2S or 3S battery. You do not need sensors so a 3650 or 3660 with a 2500Kv rating will also be enough. I have 2x 23 turns brushed in my starterbox, These are motors I had from some stock racing back in the days.

I think 2 brushless motors which are by belts mechanically hard connected will be difficult to synchronize?

On Ali you can find several of these PCB's 75W 200W DC Borstelloze Motor Drive Control Board 6V-24V High Power Borstelloze Optische Drive Harde Schijf Fan Motor Snelheidsregelaar - AliExpress