Interfax - Harmonic Percolator

[DougH]

Okay, I got some 1n695's today. Look forward to breadboarding this soon.

[JJ Gabor]

Thanks Doug.

where did you get your 1n695s from??

couldn't find them anywhere...

I did read that thread a while back and gleamed quite a lot of useful info from it. Loads of ideas for the breadboard.

[theblackman]

looking forward to hearing the results of this

[theblackman]

http://cgi.ebay.com.au/Boutique-quality ... 7C294%3A50

i wonder what diodes this guy is using his one sounds pretty good from the demo.

[JJ Gabor]

I think Timhulio is a member here. I know he is a member of the OSG forum where i sometimes post.

His percolators sound like mine with 1n34s or 1n60. NOt quite the same as the collins clone a little more treble on the clipping side. Nice effects, his new telstar pedal looks fun.

[DougH]

Thanks Doug.

where did you get your 1n695s from??

couldn't find them anywhere...

I did read that thread a while back and gleamed quite a lot of useful info from it. Loads of ideas for the breadboard.

I picked them up from a local surplus electronics place. They only had a few and I got 4 of them. If you google for them I've seen places selling them. I'm going to measure the fwd voltage on them first.

[gus]

I have a question about the voltage readings.

Q1 both the base and collector are 1.46VDC?

Ic of the NPN 9-2.49= 6.51VDC, 6.51VDC/91K=.0715ma

collector voltage drop of PNP .0715ma x 20K= 1.43VDC close to measured could be due to tolerances of the resistors
Both Ics(collector currents) are the same as they should be

So next NPN B to E drop =1.93-1.61= .32VDC
PNP E to B 1.61-1.46= .15VDC
PNP B and C both 1.46
PNP E to C .15VDC

Looks like both transistors in the circuit are biased more to saturation(higher gain) AND the series connection and no "current paths" except via the collector resistors(why I checked the Ics and voltages drops with Ohms law to make sure they matched) I guess they settle in at stable DC points. So hfe and base to collector resistors are something top be aware of.

Thanks for the voltage readings.

[Paul Marossy]

I built that Barge Concepts "clone" of the Harmonic Perculator for someone. I thought it was a pretty cool sounding thing.

[JJ Gabor]

I have a question about the voltage readings.

Q1 both the base and collector are 1.46VDC?

I have just checked the readings again and can confirm they are both the same.

[DougH]

http://cgi.ebay.com.au/Boutique-quality-Harmonic-Percolator-clone-Shellac_W0QQitemZ200348049349QQcmdZViewItemQQptZUK_Guitar_Accessories?hash=item2ea5ac9fc5&_trksid=p3286.m63.l1177&_trkparms=240%3A1318%7C301%3A1%7C293%3A1%7C294%3A50

i wonder what diodes this guy is using his one sounds pretty good from the demo.

That clip sounds pretty good, pretty typical of the sounds I've gotten on the breadboard and with the Brick. Seems more bassy but IIRC I was still using .1u coupling caps in the Brick. I'll have to breadboard this latest schem and see how it sounds.

[JJ Gabor]

Any word on the forward voltages on the 1n695s ?

[RnFR]

Any word on the forward voltages on the 1n695s ?

yes, i'd like to know as well!

[Fuzzer]

Unless you were asking for actual measured values,

I noticed that the 1n695 datasheet indicates a 1.0 fwd voltage drop @100ma and .5v @ 10ma.

Here is the link to the datasheet;
http://www.datasheetarchive.com/1N695-datasheet.html

[RnFR]

well, it lists almost every Ge diode on the sheet as having a 1.0 drop. even 1n34a's and 1n60's. now as far as i know, that's not accurate. i have some 1n66's and those are definitely not at 1.0 either.

[JJ Gabor]

Yeah I gave up on the datasheets in that respect. I have datasheets for the 1n695 and 1n595s. I have a Collins clone and there is no way the diodes sound the same as any of the other germs i have tried.

[theblackman]

possible source for the 1n695 diodes

https://www.pacificgeek.com/productdeta ... D=2522911#

[DougH]

Smallbear has the 1n695 diodes now.

[DougH]

I breadboarded JJ's schematic last night and it sounds great. I wrote it up in the perc thread at diystomp (I'm tired of typing). The 1n695's sound great, better then 1n34a's even though the fwd voltages measure the same, .223v.

[JOHNO]

I tried my hand at this one again last night. This time i built the npn version but it sounds all farty like the pnp npn version I built. I'll try two ge diodes in parallel on each side.

[Fuzzer]

The 1n695's sound great, better then 1n34a's even though the fwd voltages measure the same, .223v.

Must be the Knee then.