I currently run my machine on a single 24V power supply with a 24v-12v converter (for a laser sensor & camera) and a L7805CV regulator for powering two Teensy 4.1 with 5V.
Recently added the second Tensy 4.1 for the stepper motor and now I experience reboots after a while because the Teensy’s crash and reset.
Hooked up an oscilloscope to the 5V and ground of both Teensy’s and I see a voltage drop and spikes at the time of reboot.
I tried adding 0.1uf capacitors at each Teensy power input and that didn’t fix it.
So my next plan is to add a 5V power supply to isolate the Teensy’s from the main 24V supply. I’m not sure how to do it, I did my best guess in a diagram that you can see below, let me know if that could work?
The main Teensy is sending serial commands to Odrive and motor Teensy so grounds are all inter-connected.
How about using 2200µF or 4700 µF capacitors connected as close as possible to GND and Vcc of the teensys that "jump-in" to equalise the voltage-drops?
Thats'a good guess, but I think it's ok - The 7805 is getting 12V (from the 24v-12v converter) and It is on a heatink + 40mm fan on it. I burned my finger once and added all this afterward it runs cold'ish now.
Thanks Stefan - I was recommended 0.1uF on both Teensy's power inputs. and I also added some right at the L7805CV 5V regulator.
I'm really a novice in electronics and not sure what capacitor values to use - I can definitely try the values you proposed and see if it helps. Would be a lot easier than adding a second 5V PSU in the system.
Copied form one of my other posts:
A suitably sized large capacitive reservoir could hold up your Arduino. Measure the Arduino's current drain. Determine the nominally supplied voltage and the voltage it can fall to before resetting. i=C dv/dt, will give a capacitor value, I'd add a fat margin to be safe.
I have a similar (but different) problem. I was going to mod my laptop power brick to include a fan (because it keep getting super hot and shutting down). However, the problem is that the fan(s) are, well, noisy.
So I created what is effectively a "low-pass filter" with a big (500uF) cap and about a 102 inductor (it's a speaker) and this dampen the spiky current draws to a smooth sine wave, which I think is good enough.
You power the teensy (and other "control logic" with 24V to 12V step down and a power regulator. I feel like it make more sense to get a DC-DC switcher (rather than a low dropout regulator) and directly step it down to 5V. If things such as "24V to 5-20V USB-C power delivery" exist then there must be 24V-5V switchers.
How? Doesn't the 24V supply have huge internal capacitors (10nF and upwards)?
Also. When does this "huge voltage spike" happen? During motor movements? or else?
Is the 24V supply having hiccups?
Your scope must be able to tolerate 24V input. I want you to scope that. And the 12V when the system "reboots".
Beautiful instrument, by the way. A true scope I have never own and can only dream of. The ADALM1K is close, but it won't do higher voltages.
it runs cold'ish now.