Silver Sabre

[Alan Craik]

I built the circuit.I haven't worked on the coils yet ,but using a couple
of temporary coils,I manage to get some kind of signal right through
the circuit,
I'm don't fully understanding how motion detectors work and one part of the circuit in particular has me baffled,the little section using a 2n2907 and a tis75,where the -v connects to the base of the 2n2907 (not sure what this circuit is meant to do).I get plenty of amplification with this circuit disconnected
I now intend to make the coil but can anybody explain the operation of the motion circuit or the sub-circuit I mentioned?

[Robert Hoolko]

Re: Silver Sabre

The 2N2907 + TIS75 looks like some kind of power-on circuit like a battery test. Does the detector beep when you first turn it on? If so, this is the circuit that causes the beep. If the battery falls below a certain level it probably will not beep when you turn it on.

Robert

[Massimo]

Re: Silver Sabre

I confirm, that part of circuit is the battery test, when you swich on the circuit you have a acustic note for about 4-5 secods, when you have not acustic note you must change battery.

[Carl]

Re: Silver Sabre

The subcircuit is, indeed, the start-up battery check. With a good battery, this thing generates enough current to rail out the audio, causing a full-volume blast when you turn on the circuit.

On my Bandido III uMax, I replaced this obnoxious method with a bicolor LED. When the battery is above 6v, the LED glows green for 3 seconds. When the battery is below 6v, the LED glows red. However, this circuitry is different than the Bandido, and would need more redesign.

The SS is pretty simple, with two channels: an all-metal, and a disc. In AM mode, the disc channel does nothing, and there is no high-pass filtering that requires motion, at least in pinpoint mode. In disc mode, both the disc channel and the AM channel are fed to LM393 comparators, and both channels have to trigger to get an audio response. In this mode, they are also both high pass, and require motion.

This brings up a potential schematic error. The one I'm looking at is the "W. Lahr" version, and the LM393's are lacking resistors on the outputs. They need to have these, otherwise the comparators could fight each other and damage the outputs. The Bandido has 4.7k's.

- Carl

[Alan Craik]

Re: Silver Sabre

I just want to thank those of you who responded to my cry for help,lol.
This forum goes from strength to strength I have lurked in the background for quite some time and the technical information which is available never fails to surprise me.I can't wait to see some commercial schematics,especially the fisher 1266.I have a feeling that most of them will be too daunting a task for most home constructers but it would be nice to have a look.
Happy New year everybody and keep up the good work Carl.

[Sean Goddard]

Re: Silver Sabre

Quite Right Carl.

I've found this circuit wont simulate on Mentor without at least 10R resistors.

Considering Mr. Lahr works for Whites, I would have thought that he would've got it right.

BTW I traced the Eldorado the same way, and found, guess what? IT'S THE SAME. We'll almost, just 1 1/2 S Sabres.

Looking at other Tesoro designs (Cortez included) they ALL look the same. New money for OLD rope, or just lack of creativity on Tesoro's part?

[Carl]

Re: Silver Sabre

>BTW I traced the Eldorado the same way, and found, guess what? IT'S THE SAME. We'll almost, just 1 1/2 S Sabres.

>Looking at other Tesoro designs (Cortez included) they ALL look the same. New money for OLD rope, or just lack of creativity on Tesoro's part?

Just finished tracing the Golden uMax, it's a Bandido with a uController to generate tones. Tesoro is well-known for re-using designs. Strangely, one of their better designs, the Lobo ST, has not been re-used. There is a rumour of a new Tesoro on the way, I'll bet based on the Lobo.

- Carl

[Norbert]

Re: Silver Sabre

The LM393 is open collector.
So it doesn't need a resistor.

Or am I false?

Greetings from Austria
Norbert

[Sean G.]

Re: Silver Sabre

This isn't a motion machine, it's a continuous "auto tune" machine.

Crude, but VERY effective.

A case of Jack Gifford keeping it simple!