Does it seem like the degree of glitching has been reduced, is the same, or worse with those 2 changes?
An LM7805 could support your 5 volt rail depending on how you implement it. The higher the input voltage, the hotter it gets. If you can adjust your buck module to 8 volts, then put the 7805 after the buck module and see if that works. If your buck module will not go up to 8 volts, you could try using the 7805 directly from 12 to 5 volts if you're not pulling more than around 0.75 amps (power dissipation (heat) is increased because of the greater drop from 12 to 5 as opposed to 8 to 5). If that doesn't solve the problem then improving grounding is the next way to go. Ground paths ideally are short and use larger conductors. Having long, narrow ground wires strewn about may certainly be contributing to glitches from noise and undesirable ground loops. On Wed, Nov 20, 2019, 11:35 AM Richard Scales <rich...@scalesweb.co.uk> wrote: > I tried the first two suggestions and thought (initially) that all was > good but upon watching in detail it would seem that it is the same. > > I have a L78M05 to hand - is that going to do the job? > > Otherwise I can get something like this > https://uk.rs-online.com/web/p/low-dropout-voltage-regulators/1246447/ very > quickly. > > > > On Wednesday, 20 November 2019 15:33:20 UTC, Kevin A. wrote: >> >> Here would be my first 2 suggestions in changes to your circuit: >> >> #1: I would definitely place the ground from my logic circuits straight >> to the main power ground, instead of routing it though the 5V buck module. >> The buck converter is also a switching power supply and this could very >> well be coupling noise through the rest of your circuit, especially if it >> is the only ground path for the logic. >> >> #2: If #1 does not fully alleviate the problem, I would try placing an >> electrolytic cap of between 100-470uF on the 5 volt rail close to the logic >> circuits. This could help decouple the logic from any noise entering >> through the 5V rail. >> >> Finally, if the above two do not solve the problem, I would use a linear >> regulator after the 5V module to provide a clean 5 volts to your logic >> circuits. It looks like the 5V module has a trim pot on it, so I would >> increase the voltage to 6 or 7, and then use a 5 volt LDO (low dropout >> regulator) to provide the final 5 volts. This certainly will alleviate a >> large amount of noise on this line that you might not even be able to >> observe on your scope, unless you zoom in quite a bit on the vertical >> (voltage) scale (so that you're looking at hundreds or even tens of >> millivolts per division). >> > -- > You received this message because you are subscribed to the Google Groups > "neonixie-l" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to neonixie-l+unsubscr...@googlegroups.com. > To view this discussion on the web, visit > https://groups.google.com/d/msgid/neonixie-l/7e183735-7ca9-4287-8cc8-51e22a65d43f%40googlegroups.com > <https://groups.google.com/d/msgid/neonixie-l/7e183735-7ca9-4287-8cc8-51e22a65d43f%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to neonixie-l+unsubscr...@googlegroups.com. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/CALcVLK%2BE2k-NgwGwfhDSpkYWRQqTFFz-fc64HtH-7CHbW6S1OQ%40mail.gmail.com.
