T&L Publications

Just wanted to thank everyone for their advice. It gives me something to go on, and get these parts to my students. I found an ISD-cob part at Digikey that might work. Allelectronics does ship to Canada, although that SAW figurine is pretty scary. I assume my students can unscrew the base and steal ...

Hi, I'm a teacher in Canada, and have 2 students creating Peanut-Butter Monster Detectors from a past issue of NandV. All of the parts are easy to pick up except for the dreaded sound module. Radio Shack 276-1323 As RadioShack doesn't exist in Canada, I need to find an alternate part, or someone wit...

Just a quick update... A 2-wire switch (connecting common side of switch to ground and parallely resistor to +5 to make it a pullup) seems to have really helped. I still occassionally get a phantom dim output light. But it is sufficiently different from an 'on' that I can explain it to my students. ...

Thanks for all the help, I really appreciate it. Sounds like the first (and easiest) thing to try would be to switch to a pull-up resistor. It's a 2-wire change. That in itself may fix my problems. I have a mixture of TTL and CMOS chips, so this might also explain why my testing didn't always produc...

Thanks for the comments everyone! I understand the idea of debouncing, and I appreciate it's a much better way, but it's not entirely practical for what I'm doing and some manufactured trainer boards seem to get by without it. As for using a pull-up. I guess I'm a little unclear. I tied the switches...

The lack of resistors was my mistake. There are 1Kohm resistors for all output LED's. Originally I planned to use the same 4.7Kohm as the input but I guess green LED's drop less voltage as they were very dim.

Hello everyone, I am a teacher who has to teach some Digital Electronics to students not knowing much myself. I've admired many of the Digital Logic Trainers I've seen (power connector, input leds, output leds, breadboard, etc) that I've seen, but we can't afford these things which are $60-200. So I...