vibrato---a junk box build

[lightningfingers]

Heres a strange little vibrato circuit, made from parts I had in my junk box. One transistor phase stage, and a phase shift oscillator. Both transistors I used were 2N3904's, I had lots of fun trying to get the oscillator to work with these low gain transistors. If a higher gain transistor is used, the 3k9 resistor can be changed to 2k2, probably to get a faster maximum speed. No depth control, subtle enough not to need one.

I really like the sound, lotts of hiss and hum, from the unshielded plastic box, sounds like a warped record.
Heres a pic from my no-res phone-camera

---Enjoy---

[birt]

hmm i might build that into the same box as my green ringer

would you put it in front of the GR or after it?

[lightningfingers]

Probably after the Green Ringer, a distortion before seems to bring out the pitch bend more. On the other hand with the amp cranked it kind of gets lost.

[Paul Perry (Frostwave)]

Good one, Lightningfingers! that circuit is much more 'interesting' than it first appears :wink:
I havn't built it, but it looks like there is not only tremolo, but some phase shift as well.

[birt]

why is the schematic in 2 parts and where should they be connected?

[MartyB]

I think the LDR is a light-dependent resistor that the LED shines on, i.e. a diy optocoupler.
MartyB

[RDV]

why is the schematic in 2 parts and where should they be connected?

1. Because the LED and LDR are to be physically connected but their circuits are separate.
2. 9v+ & ground.

RDV

[Paul Marossy]

What did you use for your LDR?

[Alpha579]

you could use a jfet as a variable resistor as in Tims wobbletron if you didnt want to do the whole optocoupler thing,
nice work!
ALex

[Alpha579]

http://www.geocities.com/tpe123/folkurban/fuzz/snippets.html

[lightningfingers]

What did you use for your LDR?

Its a regular 5mm photocell, I measured 1M in total darkness, and about 100R with a laser pointer shining on the lens. :wink:

[birt]

What did you use for your LDR?

Its a regular 5mm photocell, I measured 1M in total darkness, and about 100R with a laser pointer shining on the lens. :wink:

you got a picture of such a photocell?

[Ge_Whiz]

you got a picture of such a photocell?

http://www.rapidelectronics.co.uk/rkmain.asp?PAGEID=80010&CTL_CAT_CODE=&STK_PROD_CODE=M29399&XPAGENO=1

[Paul Marossy]

Cool, thanks for the info. Looks interesting, I might have to breadboard it.  :wink:

[RDV]

If you put an electrolytic cap(say 22uF) between the LDR and Q1's emitter, wouldn't you have a tremolo then. Make it switchable and have either?

RDV

[birt]

you got a picture of such a photocell?

http://www.rapidelectronics.co.uk/rkmain.asp?PAGEID=80010&CTL_CAT_CODE=&STK_PROD_CODE=M29399&XPAGENO=1

i think i've got one of those from a camera

[lightningfingers]

If you put an electrolytic cap(say 22uF) between the LDR and Q1's emitter, wouldn't you have a tremolo then. Make it switchable and have either?

Cool Idea! I'll get another one on the breadboard and see. It also occurred to me that 4 stages with staggered cap values and an input buffer might make a decent low cost/low power univibe.

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