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4148 for 1n914?

Started by Vinnie500, September 09, 2016, 05:37:53 PM

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Vinnie500

I put a phantom octave on the bread board based on http://effectslayouts.blogspot.co.nz/2015/12/fuzzhugger-fx-phantom-octave.html

I had to replace the 4148 with 3 1n914's, I read that was an acceptable substitute  :-\

Any way it doesn't work, voltages at the 386 pins seem ok, and my audio probe works up util the first diode.

So I'm wondering is the diode sub an obvious flaw and I should wait till I've got some 4148s (about a week) or should I keep trouble shooting?

PRR

They are the same part. '4148 is newer and better-specced than old '914.

That's not your problem. Need more clues.
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Vinnie500

Cool thanks back to the garage it is then. I'll get some more clues or maybe even get it working.

Vinnie500

#3
I can't work it out I often get confused following layouts to breadboard and I can't find a schematic for this one.

The pin voltages are
1 - 8.6
2 - 7.9
3 - 7.9
4 - 7.9
5 - 8.6
6 - 9.1
7 - 8.6
8 - 8.6

Oh and signal at pin 3 is very weak

PRR

A schematic would help a lot.

However NONE of your pins is anywhere near zero. We would expect at least one at 9V and one at zero so the chip can eat a full 9V.

Ground not connected.
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Vinnie500

Hi thanks PRR, I was missing a ground link.

It's working now and sounds great (if you like splatting synth sounds with some sub octave).

Cozybuilder

I get this schematic by following the layout:
If you want to improve the power supply filtering, simply wire in a 47R resistor after D3, before the 100uF and 100nF caps.
Some people drink from the fountain of knowledge, others just gargle.

Vinnie500

that's awesome thanks heaps, you should see the schematic I came up with :icon_redface:


Vinnie500

If anyone uses the above schematic or the original layout at the top of the post I found the circuit worked better if the diode coming off pin 2 was reversed, the led started lighting up when I played at the octave was very obvious.

I also found this circuit varied a lot from guitar to guitar, the whole spectrum great to slight ticking sound (piezo admittedly)

Vinnie500

#10
Here is a link to the schematic that works. The led and one of the diodes is switched around compared to the one cozybuilder drew based on the original layout from effectslayouts.blogspot