EZ 'Improved' [?] Phaser Questions.

[petemoore]

Still I try to remove the perfbugs from the 90/180 PLUS Phaser from GEO I'm assembling.
 ...this morning I thought of this question
1  how many actives need to be installed into their sockets to get 'normal' voltage readings on a
2  Is this a phase 90 type phaser enough to call the LFO section phase 90?
 Here's some not so easy ones...
are some parts more important than others in this circuit for obtaining the Vref=3V
 As long as I'm using a diode, with a squiggly line like the one on the schematic, heat sink removed from an old board, tested, inserted to PS'd circuit [10.34v of 11.22v supply read at Vref=3V point when my board is powered], then diode checked after insertion should I be OK ? ...in other words I think I stuck a zener in there, powered it up, and then retested the zener. ...anyone know what value zener this uses ? 5.1v zener ? what'ss the other zeners at RS votage ratings...hmm anyway..if I know the part I'm supposed to be looking for, seems it would be easier to actually find it.
 Since it says 3V right there, I'm guess in a circuit that works right [I'm measuring over 10v there on my board] a 5.1 zener would work.
 Anyideas on how to check for the bias problem on my board are very much welcomed... :wink:
 I'm going through measuring resistances, confirming continuities, confirming non-continuities, tracing through using the DMM on voltage, resistance, and continuity settings. I did find some 'thing's this way already..I think I'm doing pretty good really, but Vref=3V disagrees with the measurements I'm getting at that point on my board, and the opamps don't look like they could work because of the bias measurements.
  Hmmmmm...I drooled on it, getting all hungry for the big 6 stage effect  ...ya know how it is !!!
 I'll need to try some more different than j201 Fet's in some of my fet phasers anyway, but it'd be nice to get this board working a bit anyway in the interim period...maybe get a little sweepage happening on it !!!

[R.G.]

Still I try to remove the perfbugs from the 90/180 PLUS Phaser from GEO I'm assembling.

I always think of perfboard work as the gift that keeps on giving. Expect to manually verify **everything** on a perf setup at least once.

1 how many actives need to be installed into their sockets to get 'normal' voltage readings on a

For all the non-LFO opamps, you only need the reference voltage to be good and then one opamp package at a time.

2 Is this a phase 90 type phaser enough to call the LFO section phase 90?

Yes.

are some parts more important than others in this circuit for obtaining the Vref=3V
As long as I'm using a diode, with a squiggly line like the one on the schematic, heat sink removed from an old board, tested, inserted to PS'd circuit [10.34v of 11.22v supply read at Vref=3V point when my board is powered], then diode checked after insertion should I be OK ? ...in other words I think I stuck a zener in there, powered it up, and then retested the zener.

If you put  a 10K and the "zener" across a voltage and you read 3V across the zener, all is well - at least with the zener voltage.

...anyone know what value zener this uses ? 5.1v zener ?

Um, yeah - it's 3V. Actually, I think it's 3.2V, but you're looking for a voltage value there of 3V to 3.5V, and any way you get it is OK. You can use one zener, or a string of diodes, or an LED and some diodes, or a 3V battery. The opamps don't care.

What I found interesting in your other question is that the voltage at the pins being driven by the "3V" signal are sitting at 9/10 of the power supply. Mother Nature is telling you that those pins are not being pulled to 3V from the local ground. That could be because the "3v" supply is not, or because the "3v" supply is not grounded, or because the + pins are not actually connected to the "3v" supply.

what'ss the other zeners at RS votage ratings...hmm anyway..if I know the part I'm supposed to be looking for, seems it would be easier to actually find it.

There's a half a dozen types that do 3.2V. No one part is "right" Even forward biased diodes adding up to 3.x V works.

Since it says 3V right there, I'm guess in a circuit that works right [I'm measuring over 10v there on my board] a 5.1 zener would work.

Use an approximately 3V zener.

Anyideas on how to check for the bias problem on my board are very much welcomed...  

Hook the black lead to ground. Probe both ends of the 3V zener. One end should be 0v (that is, shorted to ground) and the other should read about 3V. Then probe the + pins. The + pins should be at the exact same voltage as the end of the zener that's not ground.

but Vref=3V disagrees with the measurements I'm getting at that point on my board, and the opamps don't look like they could work because of the bias measurements.

That's either because your zener is not a 3V zener, or because on end's not grounded. The opamps are doing their best, but they are being told to go to the + rail.

[petemoore]

Very good. I was thinking that zener had to have something to do with that 3v ref. Because the voltages there [and 'everywhere'] we're way off, and the fact I hadn't necessarily the right part added to my suspicion of a problem around that section of the schematic.
 Now I'm off to see the Wiz...wait...I he just 'saw' me...no I'm off now to see that RS guy, hopefully he's got some zener types there.
 Thanks RG !

[petemoore]

While running around the park with the loose doggy of mine...on the way to RS...
 I think I may run a string of aa batteries down a tube, using a tap plate between a gnd. plate and the second battery for 3v there, and a V+ plate at the end of the 6 cell string.
 Well back to the Lab.

[petemoore]

That helped !!1
 I have two fresh 1.5v alka aa's running parallel between ground and where the diodes were.
 Opamp voltages and are all good looking, most sound to be functioning [inputs 'livlier' than outputs or at least passing signal].
 The last half of the last OA, which I used as the LFO driver [anyway has two lugs of a 500k pot between output and an input] is producing a cyclic voltage wave between .0X v and around 9v...must be that part of the LFO's working.
 Perhaps these Jfets are simply failing to cause any discernable sweep.
 Other notes:
 the Mix pot gets louder/clearer when turned toward the last sweep stage's OA output.
  The other pots had no noticable effect.