Vco-1 pulsewidth pitch problem

[oculus]

hi i just breadboarded a VCO-1, im using thomas henry 15volt powersupply i just finished to power it up.
the vco seems to work fine, but the only thing is that, when i increase the pulsewith the pitch also seems to go a little bit up
along with the pulsewith

the pitch drops almost a semitone from almost full left to almost fully right
on the pw knob.

Anyone have an idea what might be the problem?



btw i don´t have a tempco in the VCO-1 yet im waiting for it to arrive
but don´t think this should affect this problem,(in fact it track quite well without the tempco)
thanks kind regards
Oculus

[alanwilder81]

hello there,

are you still on breadboard?
it may well be a poor grounding issue. I had the same problem with my Thomas Henry 555 VCO.
when sweeping the PWM the VCO pitch horribly fluctuated.
I sorted it by adding a few more ground points from the VCO breadboard GND straight to the power supply GND and it worked

[gabbagabi]

after a quick look over the schematic i would try to remove / lower R45 and raiseR12 to 10k and R7 to 5k

[alanwilder81]

hey
what schematics are you referring to?

[gabbagabi]

sry your rigth
http://www.birthofasynth.com/Thomas_Henry/pdf/VCO-1/vco1_schem2.pdf

[alanwilder81]

no worries g.gabba !

i built the 555 VCO by Thomas Henry only. And not the VCO 1 yet
so i can't tell.
May i ask you to explain what the resistor value modifications would add to, or improve the PWM section?
cheers

[gabbagabi]

nice one !
i understood that oculus had breadboarded the th-vco1

regarding the resistors: oculus has described a strange behavior of the PWM section, so i tought:
2.2M is getting close to the "internal" impendances of an opamp so it is getting harder for the opamp to understand and regulate the feedback current.

3k and 1.8k on the out put gives a power consumption of only 3.125 mA from the (20-25mA the opamp can deliver), but, even that can result in strange behaviors under unfortunate circumctances like breadboard, opamp from bangladesh, no stabilizing caps..
and what i forgot in the previous post: ground the metal-capsule of the pot - no joke

gl
hf
gabbagabi

[alanwilder81]

thanks g.gabba

[gabbagabi]

in my strange mix of portuguese and italian:
non sei para o que ma,
niente

[alanwilder81]

where are you from ? portugal?

[gabbagabi]

ich bin ein berliner! - io so berlinese!

but my wife lived 8 years in fregene so she is even able to speak romanatio and now we are thogether in mosambique where they speak portuguese.
so i picked up a funny mix of those latin linguas.

ciao
buona notte

[alanwilder81]

it must be fun to live in Berlin

[wackelpeter]

Nope...

In recent times Berlin is overrun by hordes of hipsters...

Hipster apocalypse - the night of the living beard



Best thing to emigrate into a hipster free - safe zone like Mosambique

[alanwilder81]

bastian are you from Berlin?
its electronic music scene has always appealed me. Techno and minimal.
And after watching Depeche Mode interviews,where they sing the praise of 1983-1986 Berlin night vibe i got really curious to sample it

but the city turned into something completely different to the mid 80's,apparently.

[gabbagabi]

may enjoy a documentary about the tresor?
https://www.youtube.com/watch?v=SGGA3a_8Crs&t=790s

and if u not afraid about streaming a docu about berlin-west in the 80's
http://vidzi.tv/xg6o9y79djup.html

there is a third one about Skaters and Music in the 80's in East- Germany,
but i could not find a link for that, more info here
https://www.amazon.com/This-Aint-California-Ronald-Vietz/dp/B01GWC68Z0

all very well done, its always hard to find sleep for me when i watched them, cos those where my golden times

and very sorry oculus! for missusing ur thread but nowadays is so less communication here on em

mosambike could be a nice place if i only could find well-working Potentiometers here:-)

cheers

[alanwilder81]

don't worry g.gabba about going off topic
since the creator of this thread can't seem to be active anymore here, we can take advantage of this space and swap some infos and opinions.

However it looks like that electromusic is getting more and more quite.
I've only been here for a year but there seems to be definitely less action.
what do you reckon?

[wackelpeter]

No, i'm not from Berlin but many Hipsters from my hometown moved to Berlin (sadly not all of them).

Regarding the movies mentioned before that Documentation/Film by Mark Reeder is really recommended. This can be found on YouTube to i believe.
The link provided here has some suspect looking adds...

Btw. any Progress with your 555VCO? Did you already looked at it with an scope?

[alanwilder81]

hey Bastian,
i will take a look at those movies soon !
As far as the 555 VCO...well, no, i haven't checked it yet. it got a bit negleted in favour of some other little modules that were in my to-do-list, but definitely tonight i'll check the signals amplitude.

hipsters are ubiquitous.
even is southern Italy, where i am from, they mushroomed
not my cup of tea. Both their look and their attitude piss me off to no end

[alanwilder81]

if you ever come to Sardinia island on holiday, drop me a line!

during the summer many Germans seem to enjoy our beaches and...beers too

[alanwilder81]

so,

i scoped up the 555 VCO output signals , and the amplitude of all waveforms stays consistent through the whole frequency sweep.

However, it still puzzles me that the voltage read on DMM changes upon frequency value.

The saw tends to be even , about 2 V
the square varies from about 1.8 to 4 V

[gabbagabi]

good morning guys,

i wish i had a peroni , next time i will bring some from South Africa.

The hipsters, they really like the long wished product of that secrect circle that is stearing the world. They are the pre-version of the brainless-working-eating-consuming-and-feel-good-about-drones that they wish to have to
They are really the enemys of us natural born DIYselfis.

Regarding the DMM measurement, i would say its because cos a DMM does filter the incomming signal.

Regarding this thread i finally realised that it is from 2013

About the quantity of communication here on EM, my guess is we should do what we are doing right now, going a bit more personal.
I really love this place, did not seen any other worth it. guys are also on Muffwiggler but for some reason i cant leave this place.

What else? The film. They somehow deleted the Berlin Docu on youtube.

cheers
gl
hf

[alanwilder81]

hey g.gabba,

Yes, i think it's a nice thing to become friends here, and make some more "private" lines of communications, for a lack of a better term
And besides the electronic DIY side it's nice to get each other a bit, talk about life, it won't harm !

Now someone brought in the Hipsters topic, which would have me talking about that forever. This trend,along with many others,it's something i love to analyze. It tells a lot about our society.
They claim to be strong anti-capitalists, to have anti-consumerist attitudes (but that doesn't apply to Apple or Ray-Ban they buy)
and in short ,those scumbags are consumers of culture, not producers of original content whatsoever. Better forgotten.

Peroni is an ok beer ,yet it's considered quite average over here.

[alanwilder81]

back to the 555 VCO, it sounds awesomely good, it has that unmistakable "80's" flavor to my ears.
Can't wait to couple it with a Roland filter to get the best out of both modules

[gabbagabi]

alan,
lets open a thread in the chat room area and leave this here.
cu there

[alanwilder81]

hey g.gabba

i don't know how the chat area works !