BLISTOOL LTC48

[Patrick]

hello

good work, please more details,
partlist, corrected pcb etc.
would try it

regards

Sorry,
I have no other details.
Only images of the PCB

If anyone can make better pictures or read components.

[Patrick]

The other end of C17 is wrong - goes to U4. Also Q11,Q12 look wrongly connected.

Q11 and Q12

[spookmore]

ron_c

ron_c;146443]spookmore, I tried to answer your PM concering the schematic you ask about, but I'm not allowed to send a PM to you, PM me again with some sort of contact information.
i got your message you can get me on [email protected]

Regards

Norman

[spookmore]

Thanks

Spookmore, as you're UK based, a good place to start would be to take a look at the kits produced and sold by 'Silverdog',- website has that name.

Skippy,thank you for your advice i really appreciate it i am urgently want to manufacture my own metal detector.

Big thanks again

Norman

[Rumcajs]

Q11 and Q12

No. it is an low-cost replacement for special, (fast and very low reverse-current) diodes.

Here is an Hungarian Fischer 1212-variant: see T4, T5 and T6 transistors.

[Skippy]

I suppose in practice, it doesn't matter whether the base-emitter or the base-collector junction is used as the diode, I was more familiar with the base-emitter circuit, as shown on rumcajs' circuit, and had not noticed the Fisher way was different. I have also seen other ways of connecting bipolar transistors and jfets up as low-leakage diodes. Because it's a leaded component layout, you could easily try the other methods.

[Rumcajs]

I suppose in practice, it doesn't matter whether the base-emitter or the base-collector junction is used as the diode, I was more familiar with the base-emitter circuit, as shown on rumcajs' circuit, and had not noticed the Fisher way was different. I have also seen other ways of connecting bipolar transistors and jfets up as low-leakage diodes. Because it's a leaded component layout, you could easily try the other methods.

This circuit is not my plan, I just to indicate what is transistors use that diodes.
You're right. Unfortunately we do not know why the designer used different junctions, or why not? diodes, but own documentation involves the Fischer-basis (publ. in the Rádiótechnika Évkönyv, Budapest 1995).

[Skippy]

In English, 'Rumcajs' circuit' does not mean you are the author/designer, merely that it was presented on the forum by you.
I believe when the base-emitter junction is used as a diode, the collector is joined to the base in order to prevent the collector-emitter junction saturating. As bipolar transistors do work (badly) with the collector and emitter swapped, joining the base and emitter would serve the same purpose. I wonder if the Fisher implementation is chosen because of reverse base-emitter breakdown voltage (often 6 volts). Maybe base-collector breakdown is higher? I'm curious now, I'll have to look it up.

[Patrick]

In English, 'Rumcajs' circuit' does not mean you are the author/designer, merely that it was presented on the forum by you.
I believe when the base-emitter junction is used as a diode, the collector is joined to the base in order to prevent the collector-emitter junction saturating. As bipolar transistors do work (badly) with the collector and emitter swapped, joining the base and emitter would serve the same purpose. I wonder if the Fisher implementation is chosen because of reverse base-emitter breakdown voltage (often 6 volts). Maybe base-collector breakdown is higher? I'm curious now, I'll have to look it up.

Also Tesoro

[Skippy]

This technical thread has a few interesting points:
http://www.electronicspoint.com/diod...rs-t25410.html
Seems a lower capacitance is achieved with the 'base-collector diode' method, though only for npn devices. It's also suggested that transistor-diodes are better than diodes at low signal levels(millivolts).