[sdiy] My 4069 attempt not working

[Scott Gravenhorst]

music.maker at gte.net wrote:
>If you think there may be a problem with the current sink, you can replace
>it with a resistor to ground, a 100K pot in series with 5K for example. 
>If it doesn't oscillate like that, then something is wrong with the hookup
>of the schmitt trigger, the integrator or both.  If it does oscillate, you
>need to trouble shoot the current sink.  That's what I'd do.  The output
>of the integrator should be a ramp, sawtooth wave.  The output of the
>schmitt trigger should be a narrow pulse that coincides with the
>sawtooth's reset.  Your power supply arrangement sounds fine.

One more thing, with a resistor as a current source, the ramp will be
rounded, not straight.


>Nicolai Czempin <n.czempin at gmx.de> wrote:
>>Well, I got the 2.2nF Capacitor, and as some of you have guessed, it 
>>didn't make any difference to the fact that it's not working :-(
>>
>>It's kinda hard to debug when one doesn't know what to expect at 
>>different points in the circuit.
>>I tried to take some pictures with my cheap-o-the-line digicam, but the 
>>quality is so low that it's not really possible to see anything (I can 
>>basically choose between overexposed, underexposed and blurry, even at 
>>the highest resolution with the highest quality level).
>>
>>I tried to leave parts out to simplify the whole affair---only ones 
>>where I'd guess it wouldn't be a significant difference: All the stuff 
>>that's there for thermal stability is not much use when it's not 
>>oscillating at all!
>>So I eliminated the thermistors for now, and I haven't yet glued the 
>>transistors together.
>>As mentioned before, I am only using the "top half" of the 4069 IC 
>>(except for pin 7, which is connected to GND).
>>I don't have the power supply yet, so I'm using two 9V battery blocks, 
>>with GND "in the middle".
>>I have also eliminated the second input voltage, that should just have 
>>the same effect as having 0 V at the second input, shouldn't it? Or do I 
>>need to connect it to GND through the 100k resistor?
>>The V1 I'm simply connecting to +V, as I don't have any alternatives 
>>right now. But that should work too, shouldn't it? There should be 
>>*some* oscillation.
>>I did make sure that +V, -V and GND really are that, I do that every 
>>time. But I'm not sure what should happen in the different parts of the 
>>current source, and it's hard to debug that way.
>>In my childish naivety, I also tried to just leave out the current 
>>source and connect the integrator input directly to +V. Still no 
>>oscillation.
>>I'm pretty sure that I've made the correct connections (no diodes the 
>>wrong way round or anything like that). I can still post a picture if 
>>that would help anyone, but as I said they are all very low quality.
>>
>>Can someone help please? "Just" a walkthrough as to what I should see on 
>>the scope at certain key points would be very helpful.
>>
>>Sigh. I really would like to get this to work, otherwise I'll have to 
>>get back to crummy 741 stuff.
>>
>
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>-- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
>-- Linux Rex         | RedWebMail by RedStarWare
>-- FatMan: home1.gte.net/res0658s/fatman/
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>-- Autodidactic Master of Arcane and Hidden Knowledge.
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---------------------------------------------------------
- Where merit is not rewarded, excellence fades.
- Hydrogen is pointless without solar.
- What good are laws that only lawyers understand?
- The media's credibility should always be questioned.
- The only good terrorist is a dead terrorist.
- Governments do nothing well, save collect taxes.

-- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
-- Linux Rex         | RedWebMail by RedStarWare
-- FatMan: home1.gte.net/res0658s/fatman/
-- NonFatMan: home1.gte.net/res0658s/electronics/
-- Autodidactic Master of Arcane and Hidden Knowledge.