This post covers Step 2 (of 4) for Exercise 11.
Step 2 will have you adding some more components to the circuit you built in Step 1. You're also asked to add an 8 ohm speaker to the mix. I built the circuit as shown on page 86, but was unable to get any sound coming from the speaker. I checked and double-checked my wiring, but no buzzing sound... so...
I removed the speaker, added in a white LED (removed R7) and basically built the same circuit found in Step 1. As you can see from my photos, the LED stays lit... and the original circuit (green LED) blinks slowly enough I couldn't get a picture of it flashing... but it did flash at its normal speed. The white LED, as expected, stayed continually lit.
So, I removed the white LED, put the speaker back in (for a photo) and tried to listen for a buzz... but nothing. Either my hearing isn't that great or this little speaker just isn't putting out that much noise. We'll find out tomorrow, because apparently we're going to be amplifying the speaker in Step 3... if that doesn't work, I may have a busted speaker.
A few notes about this exercise:
1. My first try at powering up everything, including the white LED failed... then I remembered. Duh. I needed two small wires to link up the top half of my breadboard with the lower half. Apparently my breadboard's positive and negative voltage columns do not run top to bottom completely... so I stripped off the ends of two small wires (one red, one black) and connected them as you can see in the pictures.
2. I believe I've found an error on page 86 - the speaker's negative terminal wire is shown plugged into the negative voltage column's left-most column... should be the right-most column where R6 and C2 are connected. I tried it both ways (hey, who knows... maybe it's correct, right?) but no luck. I'm fairly convinced it should be tied into the circuit by plugging the speaker's wire into that right-most column.
3. If you don't have a .0047 microfarad capacitor, you'll need one for this exercise. You'll also need two of the 2N6027 PUTs... if you've only got one, you won't be able to finish Parts 2, 3, or 4.