Re: BASICS!-how can i make this simple recorder loop?


arthur byte wrote:

Now you need to cobble together a 555 with an NPN transistor like a
2N3904 to do this (view in fixed font or M$ Notepad):

|
| VCC VCC VCC
| + + +
| | | |
| .-. | |
| 150K| | .---o----o---.
| | | | 8 4 |
| '-' | |
| | | |
| o-----o7 |
| | | | Wire 1
| .-. | LMC555 | .------->
| 10K| | | | |
| | | .--o6 | |
| '-' | | | ___ |/
| | | | 3o---|___|--| 2N3904
| o--o--o2 | 22K |>
| +| | 1 5 | | Wire 2
| --- '---o----o---' o------->
| --- | |
| 100uF| === ===
| === GND GND
| GND
|
(created by AACircuit v1.28.6 beta 04/19/05www.tech-chat.de)

im not sure that i unerstand this diagram, but i managed to find a
great explanation of these 555 ics (for other complete beginners, go
here: http://www.uoguelph.ca/~antoon/gadgets/555/555.html)

im going to try and use the information you gave me (thank you thank
you thank you!) and combine it with the simpler diagrams in the link.
and having looked at the link above, im beginning to get a better
understanding of your diagram.

thanks again,

a-


This should turn on the transistor (and restart the ISD chip about once
every 10.5 seconds or so. Depending, it might be better to use a 180K
or 220K resistor in place of the 150K -- your call. Don't make it too
close -- cap values drift over time and with temperature.

The easiest way to supply power would be to just use an external 9V
alkaline battery for the 555/transistor circuit. That way you don't
drain the little coin cells, which look like they might be a little
difficult to replace.

Good luck
Chris

Hi, Arthur. The 555 page you referenced does have all the basics. If
you use a 9V transistor battery, have the output of the 555 drive an
NPN transistor (whose emitter is tied to the 555 common/9v battery -),
and then connect the collector of the transistor to the higher voltage
switch wire and the emitter to the lower voltage switch wire, you
should be fine.

ASCII schematics have been on newsgroups for a long time. Since you're
a Google Grouper (as am I), you might not know you have to look at the
ASCII diagram in a non-proportional font like Courier for it to make
sense. In order to see the diagram, click "Show Options" on the Google
message header, then click "Show Original", and see it in all its ASCII
splendor. ;-)

Cheers
Chris

.

Relevant Pages

  • Re: Transistor Orientation woes ?
    ... >>I found a little circuit that is suppose to test transistors. ... >>circuit shown on the right which uses the transistor as a switch. ... >>To test a PNP transistor use the same circuit but reverse the LED and the ... >>the diagram shows me the LED just comes on and stays on. ...
    (sci.electronics.basics)
  • Re: Modify Astron Power Supply
    ... The diagram looks strange to me, with a direct connection from the ... The pass transistor pre-drive transistor is a simple current amplifier. ... but DO put that crowbar SCR anode on the collector of the ...
    (rec.radio.amateur.homebrew)
  • Transistor Orientation woes ?
    ... I'm trying to test NTE108 transistor. ... I found a little circuit that is suppose to test transistors. ... See diagram below or link. ... the transistor by the pins. ...
    (sci.electronics.basics)
  • Re: Transistor Orientation woes ?
    ... >I'm trying to test NTE108 transistor. ... >I found a little circuit that is suppose to test transistors. ... >the diagram shows me the LED just comes on and stays on. ... looking at it with the flat _facing_ you. ...
    (sci.electronics.basics)
  • Re: Powering DC geared mmotor from cordless drill.
    ... you can accomplish the same thing as this comparator with ... just a transistor and three resistors, like this (view in fixed font or ...
    (sci.electronics.basics)