 |
PM |  | |
Quote | | |
Reply | | |
Full Topic | |
| Joined: | Mar 3rd, 2008 |
| Location: | Muskogee, Oklahoma USA |
| Posts: | 349 |
| Status: |
Offline
|
The 555 will trigger on its own...just running as an astable multi-vibrator. You set the trigger time with the right capacitor/resistor in its circuit. Plenty of tutorials for the finer details online...actually, this is a good circuit source too - http://talkingelectronics.com/projects/50%20-%20555%20Circuits/50%20-%20555%20Circuits.html
There's an applet thing on there as a download, so you can try out 555 circuits without building anything. Probably 'Wine' will run it.
The scan rate can be with a pot yep, i'm not sure of the value from memory, but a full sweep may be 8 seconds and, blip, the 555 will reset the scan.
The SC1088 scans on it's own, it's just the audio output of that scanning that we don't normally hear.
The simplest way of enabling and disabling the scan, is to have a 2 way toggle. One way to connect the power to the 555 circuit so it runs, the other way to disable it.
Yeah, there are such things as solid state relays, but I don't think i've ever used one.
https://en.wikipedia.org/wiki/Solid-state_relay
Freecycle is in all USA cities I would think and UK. I'd say do a search for something like 'Freecycle Grimsby' and see what comes up for wherever you live. People here use it for goat feed, baby formula and mattresses but not much else. However, if you are near a city then people may use it more. Free to advertise, free to post wanted ads.
You should find pots of lower ratings on old CRT monitors, the ones with the wheel adjustments on the front. Or anything else with a volume pot, like cassette recorders. Alternatively, linear pots are aplenty on a hi-fi mixer/EQ panel.