Experiment 11 from Make: Electronics
Hi, this'd be my first forum post. I'm really out of options here. Let me get straight to the point. I bought the book "Make: Electronics by Charles Platt" a while back, and I'm currently stuck on the very first part of Experiment 11. It is where you build the oscillator part of the circuit. I'm going to include the parts used, a couple images of my circuit (As I don't have a camera, I had to take them with my webcam), and what I threw together on Fritzing. Be aware that I'm a bit of noob, so I tried to make the Fritzing circuit look as best as I could in the time that I had to post this question. The problem is that the LED is not blinking, it is suppose to blink very rapidly due to the discharges of the electrolytic capacitor in the circuit. But for some reason, the capacitor is not building up voltage to do this. I have a feeling it has something to do with the 2N6027 transistor and how its placed. But I'll let you guys have a look.
2N6027 data sheet – it's a "PUT" – a programmable unijunction transistor.
What I've tried
- Different layouts like thisenter link description here
- Rotating the LED to observe polarity
- Ordered from a different seller, at Digikey
- I rotated the transistor, every time I did, the LED would light up, but wouldn't blink.
Parts
- Resistors: 470K, 15K, 27K
- Capacitors: 2.2uF electrolytic capacitor
- Output: Red LED
- Transistors: 2N6027 ordered here
—> http://www.amazon.com/gp/product/B0002ZPTN6/ref=oh_aui_detailpage_o04_s00ie=UTF8&psc=1
I'd appreciate any help I could get! Thank you so much!
Best Answer
It's hard to tell from the photo, so I may be incorrect, but it appears that the "G" pin on your PUT is connected to the breadboard, but that nothing is connected to a rail that it shares. It may sound like the obvious, but it helps to double check that everything is firmly connected to the board and that the board is being powered reliably (I.E. No dead batteries, etc.). More often than not, it's simple mistakes that can make a circuit not work no matter what you try. It won't hurt to double check that you have your capacitor and LED polarities correct too.