Pro Audio Design Forum

No luck with relays. It takes too many of them to cover any useful range of the log pot. I started to look in the direction of JFET switches which led me to one interestion TI app note with the schematic of video switcher. I played with it in the sim and it looks fine, I don't get any drastic increa...

I've explored the tapering option and it's not that easy. The problem is: I need the "20" multiplier for the correct taper. When I select the appropriate values for R and R' (2020k and 105k), the minimum resistance (for 16 steps, equally divided for the linear pot) is 58K which is too much...

This is most helpful! Thanks! Rheostat is what I need. Those taper "bending" resistors are very handy. Will see how it works with linear switching pot.

The attenuator site you mentioned is also a very interesting resource. Unfortunately it doesn't suite my particular need.

I'm trying to replace some obscure pots with switches. However, some switches are so large that I have to reside to relays. My goal is to minimize the relay count. Now, with linear pots it's quite simple to use 4 relays and get 16 even steps feeding binary numbers into relays coils. I can even use a...

Filter inductor? Didn't see that one. Glad you found it! (We hope.) You didn't see it because it's in another part of the circuit, I didn't post a schematic for that. Comparators are physically above the inductors, so the transients were coupling right into inductors. Had to slow chips down with ca...

Had a chance to modify the circuit as was suggested. Unfortunately, it didn't help much. I still get the harmonics from comparator oscillation

Edit: FOUND IT! This is the comparator coupling to the nearby filter inductor. Gonna see if some screening helps.

Ok. I'm going to modify the current splitter and grounding scheme and see if it helps with the issues. Here's the version with all modifications suggested in this thread: Does this looks correct?

mediatechnology wrote: ↑Sat Sep 02, 2017 1:59 pm I would lower it to 100 nF.
Also bypass the voltage divider node at the non-inverting input.
Be aware of the potential of TL07X latch-up as a follower.

Will do. What would be a better ic for this job? NE553x?

What JR said. Decouple to "real" ground. Also remove those two 22uF at the output of the TL07X rail splitter. It's not going to like driving 44uF. Add a 47R in series with the rail splitter output and then decouple the rail splitter line with a single C to "real" ground. Somethi...

Well, this will actually reduce parts count (2 caps per chip to 1 cap per chip). Will try this when I get back home from tour. Anything else to look at?