T&L Publications

Robert,
Thats a pretty low voltage to detect with just a simple diode probe. Probably will need a VHF wideband front end amplifier for best results.

My two cents worth,
Steve G

I wired this circuit up yesterday, basically trying to duplicate Ian's design and it's functioning fine after 12 hours. Didn't have a 24 volt transformer but used a 16 volt ac alarm transformer instead.


Steve G

Ian, Does the voltage go to zero if the filter capacitor is removed? If so then you need to isolate the filtered dc voltage more. Use another bridge rectifier across the 24 volt winding for this purpose. Suspect some leakage in the diode connected to the + rectifier output causing this problem Steve G

Thanks ,correction noted! Miguel, I copied the triangle from your link into "Paint" and replaced the color. Used the appropriate font size and text style to match. Font is "Century", "36" size and "Western" style for the big letters. Use "12" size fo...

Ok Externet, maybe this will help.
Steve G.

Peter,

Thanks for the reply. Did some futher research on the A/D conversion and agree with your analysis using the Nyquist criterior.
Ordered a couple of chips and will verify myself.

Steve Ghioto

Trying to find out the frequency response or -3db roll off frequency using the Winbond ISD1760 chip with a 12khz sampling rate. Nothing is mentioned in the data sheets about this. Presently using the ISD2560 chip which has a 8khz sampling rate. Spec sheet for this chip says the -3db roll off is 3.4 ...

I would recommend the Picaxe family of micros. Chips have built in radio and infrared xmit /receive capabilities. All programming software is free and doesn't require a compliler. Here's the link for all you need to get started.
http://www.rev-ed.co.uk/picaxe/

Steve G.

"Missing Pulse" detector circuit will work. This circuit is out of the 555 timer handbook. Circuit has been breadboarded and works with component values as shown in the schematic.

Steve G

SETEC_ Astronomy,

This circuit will work. Just need to adjust Rb value as specified for best audio quality. Not a critical adjustment.

Steve G

Steve,

This circuit will do the job. The voltage from the adaptor ( wall wart ) should be at least a volt higher than the battery for proper operation. The input pin on the 4550 will be high when running on battery power.



Steve G