I asked this question about 2 years ago. I did get a suggested solution, but it didn't work as I had hoped, so I'm re-visiting this project...to hopefully get it to work like I had originally envisioned.
It is based on project 11 in the 'Make: Electronics' book. It's a siren using two 2N6027 Programmable Unijunction transistors...like in the attached pic. I drew the circuit orientation left to right (like my breadboard) rather than top to bottom which seems to be the conventional orientation. My siren circuit works perfectly when I do it as shown. The bottom (audio) oscillator makes an audible high-frequency tone, which is caused to waver up and down in pitch by the low-speed oscillator upstream of it and connected to the audio oscillator's gate.
What I've been wanting to do (unsuccessfully) is add a third (very low speed) oscillator upstream of the low-speed oscillator...to make the entire siren sound itself slowly rise and fall in pitch. So I made a third very low speed oscillator which by itself works fine. But when I connect its cathode (output) to the gate of the low-speed oscillator (as shown by the grey line in my pic), it doesn't work. I even tried a whole range of resistance values for the conenction. I also tried changing the values of the resistors which set the voltage at the gate of each PUT. Still didn't work. Any help is appreciated!
It is based on project 11 in the 'Make: Electronics' book. It's a siren using two 2N6027 Programmable Unijunction transistors...like in the attached pic. I drew the circuit orientation left to right (like my breadboard) rather than top to bottom which seems to be the conventional orientation. My siren circuit works perfectly when I do it as shown. The bottom (audio) oscillator makes an audible high-frequency tone, which is caused to waver up and down in pitch by the low-speed oscillator upstream of it and connected to the audio oscillator's gate.
What I've been wanting to do (unsuccessfully) is add a third (very low speed) oscillator upstream of the low-speed oscillator...to make the entire siren sound itself slowly rise and fall in pitch. So I made a third very low speed oscillator which by itself works fine. But when I connect its cathode (output) to the gate of the low-speed oscillator (as shown by the grey line in my pic), it doesn't work. I even tried a whole range of resistance values for the conenction. I also tried changing the values of the resistors which set the voltage at the gate of each PUT. Still didn't work. Any help is appreciated!
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