looking for CScope 660 schematic

[hugo]

Hi to all,
I've got a CS660 MD for several weeks now and I would like to learn more about it..
Does somebody can share the schematic ?
Thank you,
Hugo

[hugo]

“you are never best served than by yourself”

Here is the reversed engineering schematic of the CSCOPE 660.

I still have to check some values (Coils, tuning caps, etc ...)

Regards,
Hugo

[hugo]

A small update ,

Regards,
Hugo

[Davor]

Something is not right

Tx can't work as it is drawn here, however, it just might be that something is hidden in the coil itself. Are there some other connections to coil beside red-black and white-green? In case there is a connection from Tx coil to gnd it would make much more sense.

I'm still struggling to grasp why was reset done with jfet while there is a perfectly good cmos switch just lying there unemployed. Otherwise this seem as a perfect Zen of everything I like (except maybe audio stage).

I think I like this design

[Altra]

I think its a center tapped TX coil. The center tap going to ground, one leg to the collector, the other to the rc network. The ground connection is missing.

[ApBerg]

I think its a center tapped TX coil. The center tap going to ground, one leg to the collector, the other to the rc network. The ground connection is missing.

Cscope uses a http://en.wikipedia.org/wiki/Hartley_oscillator

Look at http://www.geotech1.com/forums/showt...ghlight=cscope




Best regards

Ap

[hugo]

Thank you for all your informations !

Some things are missing :

The center tap tx coil connection to ground.
The TX & RX tank caps.
R20 value is wrong 2K2 >>> 22K
RV1 and VR2 values.

Regards,
Hugo

[aykurtelektronik]

help cscope 770D VLF TR schematıc

help cscope 770 d schema

[hugo]

Here is the modified version of the schematic.

Does someone can give me accurate datas about the head ?
Because of the tank capacitors, maybe the values I've measured are wrong ...

Regards,
Hugo

[Davor]

The only sure way to see inside, and not destroy it in a process is x-ray. However, this design seem straightforward as is and whole thing is latched to Tx oscillation. So, if you manage to make a fairly close match in resonance of Tx it should be OK.
Even if you miss by + or - 20% you are good - works the same.

[Rumcajs]

Dear Hugo,

the drawing from the cs660_2.pdf maybe wrong. For example

1. the R15 resistor must be relocating after U2A, R15/C7
2. between transmitter and receiver circuit must be an 10-12 pF ceramic capacitor
3. U5B 7pin to 6pin: parallel 100k and 10nF ???
4. the audio circuit maybe wrong missing an 22k resistor from Q2, R12 and R13 value are is 10k, missing one 1N4148 diode, R11???
5. R21 is an 470R resistor? nor an 220R?

That it is in the first circle. I have not (never) seen the original circuit, but I think that these changes are not to detriment ...
Someone works this circuit?

Best regards

Rumcajs

[hugo]

Hi Rumcajs,
You are right about the R12 & R13, they're 10K resistors.
But not for the other points, please see the photos of the pcb.




Regards,
Hugo

[Rumcajs]

Hi Hugo,

many thanks for reply and photos!
Ok, making an error-free drawing from an panel is not easy, but very good gymnastics.

Im just interested, how does this circuit and unusual solutions to meet me. For example, still do not understand the operation of Q3 without power.
It seems that to reduce the cost of mass production have been simplified to the extreme.

In the second photo, I found a capacity of 0.1 microFarads (100nF) part (between the LM358 and 4024 -- C18?) did not find that the drawing.

Regards,
Rumcajs

[hugo]

Hi Rumjacs,
Yes, I've forgotten to draw C10. It filters the supply of U1 (+5V and 0V).
About Q3, IMHO, the transistor is powered ... from 0V to -9V (Through Q2).
Regards,
Hugo

[Davor]

Q2 and Q3 form a so called Sziklai pair. Q3 is biassed deeply in C class, which is good for power efficiency, and the fact this solution is not at least bit linear is not a problem here.