3rd run for Thomas Henry's 555-VCO and Controller LFO

jukingeo · Posted: Sat Mar 22, 2014 5:24 pm Post subject:

Whoa!

I don't recall getting an email to send in payment and I checked back here and people are getting their boards?

I'll double check my emails, but I seriously don't remember getting any message that the boards were in to send in payment.

fonik · Posted: Sun Mar 23, 2014 6:02 am Post subject:

stubbyfex · Joined: Sep 08, 2009 Posts: 8 Location: Denver, Colorado

Received the PC board yesterday. Only 10 days from Germany to Denver!
Excellent quality product! Thank you very much.

jukingeo · Posted: Thu Apr 03, 2014 2:58 pm Post subject:

555 - VCO Boards received today! What can I say, they are a thing of beauty. Very good quality boards. Now I just have to recall where the BOM was for these.

So far it looks like I am WELL on my way with my custom synth.

1 - MFOS DIY Synth Experimenter
1 - MFOS 16 channel sequencer
1 - MFOS Micro Sample & Hold
3 - Thomas Henry 555 VCO's.

I think this should keep me busy for quite a while.

Thanx again Fonik for the prompt shipment on the boards. I got them in about 10 days as well.

Geo

crashlander42 · Joined: Oct 21, 2006 Posts: 292 Location: Orlando, FL (US)

Have I really missed 3 runs of the 555 VCO boards now?! I need am alert system or something. Maybe with sirens and flashing lights...

ashleym · Joined: Aug 20, 2009 Posts: 181 Location: uk

StormB · Joined: Aug 15, 2013 Posts: 18 Location: Germany

Hi,
Bin beim Aufbau des Lfo und finde die Diode D2 nicht
Laut sheet müßten es 7 Dioden sein konnte aber nur 6 bestücken
Gesetz
StormB

fonik · Posted: Fri Apr 25, 2014 3:17 pm Post subject:

dwhacks · Joined: Jul 18, 2014 Posts: 2 Location: montreal, CANADA

Would there happen to be any extra boards left? I would really like to build one, especially after watching your Youtube video of it!

jcarruthers · Joined: Jan 16, 2015 Posts: 1 Location: London, UK

Was thinking the same thing — are there any left?

fonik · Posted: Fri Jan 16, 2015 1:54 pm Post subject:

i am currently working on the how and when... so yes, new boards an panels are coming for the 555VCO, Controller LFO, and the X4046 VCO. i am still pondering about the CMOS ADSR, though.

Karlisss · Joined: Apr 20, 2015 Posts: 25 Location: Latvia (EU)

555 Successsssss! Finaly i have SIN in my diy system!
I bilt with "simple" 3906 nonmatched pair with simple 2K R11 instead of temco sinc i need just a sound sorce.
Thank you very much!

sircut · Joined: Mar 14, 2016 Posts: 5 Location: Germany

Hi there,
I am new to this forum and hope someone can help me with my problem. I´ve bought a TH 555 VCO pcb set from Thonk, builded it and put it in my case. Everything was working fine. I tested every waveform and the fm inputs... No problems. But when I put in a CV it began to sound messed up. Some kind of high frequency distortion was introduced in the waveforms. I checked the board for errors but could not find any. Now when I plug in the module again (without a cv source), the waveforms have a very low amplitude and are sounding very thin. I used the resistors mentioned in the updated BOM, but missed out the polystyrene capacitor. hopefully someone can help me, because I got really stuck.

Ciao,
Luigi

bamboombaps · Joined: Oct 23, 2015 Posts: 66 Location: Glasgow

im a noob myself but first thing id try is putting the recommended capacitors in place...

fonik · Posted: Sun Mar 20, 2016 1:27 pm Post subject:

Grumble · Posted: Sun Mar 20, 2016 2:21 pm Post subject:

Be sure to check the polarity of the capacitors for the ones that are not bipolar.
Capacitors will shortcircuit when used with the opposite polarity!

sircut · Joined: Mar 14, 2016 Posts: 5 Location: Germany

I found it! The jacks that I bought had a different pin out. They also are the types of jacks, that close the tip to ground if nothing is inserted. I had to solder a little bridge on all jacks and now it works like a charme.

Thank you all for your support, now it´s time to calibrate the hell out of them. Maybe I have to come back later with some new issues Wink

Cheers,
Luigi

sircut · Joined: Mar 14, 2016 Posts: 5 Location: Germany

Hey,
I have a new problem now. I tried to get 1v/oct right, but the closest I can get from one C to another, is 130hz to 400hz. There is no more room to play on the v/oct trimmer. I double checked everything and there are the right polystyrene caps in place. I am not shure if I got the right Tempcos (they are at least 2k ones).

I turned the trimmer all the way to the left and it feels like I have to turn it some more time to get it right.

Thanks for your help in advanced.

Lui

sircut · Joined: Mar 14, 2016 Posts: 5 Location: Germany

Nobody?
Maybe I can just swap out the 1v/oct trimmer with higher value one?

Any other ideas?

Thanks,
Lui

fonik · Posted: Wed Mar 30, 2016 2:18 pm Post subject:

sorry for the late reply, i currently do not find much time for the forum.

check the HF trimmer value first.

the 555VCO is normally an easy candidate for calibration. if it does not work from the start, then there will be an error elsewhere. i would not suggest to change any values/parts as shown in schematic. the design is proven to be correct.

sircut · Joined: Mar 14, 2016 Posts: 5 Location: Germany

Thanks for your reply!
The value of the HF-Trimmer is 100k. The writing on the trimmer is 520 B / W 104.

Cheers,
Luigi

elmegil · Posted: Thu Mar 31, 2016 12:46 pm Post subject:

Someone recently building another of Thomas' VCO's had used the wrong resistor for the other part of the divider for the HF trim.

You might check:

1) R2 (should be 390R)
2) R23 (should be 22K)
3) value of R1 V/Oct Trim (should be 100R)
4) make sure that R36 is at the low side of its settings (I think, Fonik can correct me, but it looks to me like it's set up that you want to start with the wiper at ground and slowly bring it up. What makes me uncertain is that in other of Thomas' designs you want it at the *high* side because it's limiting the amount of feedback that addresses the HF component).

Ebardie · Joined: May 21, 2016 Posts: 1 Location: England

I'm getting leakage from my Fonitronik TH-555 (and for that matter TH-X4046) to my amp modules (a Frequency Central System X Amp, and a Frequency Central Meth Amp) even when the osc and amp are the only two modules in the case and there are no patch cables installed.

The power supply is a Mean Well PD-2512 Open Frame Power Supply, distributed via a long piece of stripboard with headers soldered in every few cm.

The leakage seems to be related to the square wave since twiddling the PWM affects the sound.

Any idea what I can do to trace/fix this problem? Is it a known issue?

Thanks for any light you can cast!

muziekzen · Posted: Sat Jun 18, 2016 2:47 am Post subject: POT value

Hello everyone,

do you know if other values (such as 50k) could be used for the pots?
I have having difficulties finding 100K of the usual kind and I have some 50k.

Thanks!

Guido

elmegil · Posted: Sat Jun 18, 2016 8:25 am Post subject:

Any of the pots that are voltage dividers should be able to be any value you care to use. Lower than 100K will consume a bit more current overall, but I don't have any reason to expect that would be a problem.