King Cobra PCB

[kt315]

second section of the switch look on R53 R55

[kt315]

'mode' switch on the panel. colors of wires marked on the circuit.

[RelicHunter1388]

That information is a treasure! Thank you so much for sharing it kt315!!!


Now every piece of the puzzle falls into place. The MODE Switch is of ON-ON-(ON) type. This way, when the switch is in the middle position, the Discrimination circuit is closed and connected to the Fixed Position.


More precisely, the MODE SWITCH positions are:

ON [Left] (DISCRIMINATION) = 1MM + 1MR , 2MR + 2MM (5 + 6out , 2in + 3)
ON [Middle] (ALL METAL) = 1MM + 1ML , 2MR + 2MM (5 + 4out , 2in + 3out)
(ON) [Right] (SET ALL METALL) = 1MM + 1ML , 2MM + NONE (5 + 4out , 2in + 1out)


With the cables and poles

[4] 1ML (YELLOW) = Momentary Position Set
[5] 1MM (GREY) = Fixed Position All Metal
[6] 1MR (GREEN) = Fixed Position Discrimination
[2] 2MM (BLUE) = ???
[3] 2MR (WHITE/RED) = Discrimination
[1] NONE


Also, if every toggle switch of this type follows the same principles as the T80-T Series I referenced, then the keyway should go to the right for the momentary (ON) position to be on the right.

I also made a picture by adopting a picture from a previous post:



Now, I only have to find one of these super-rare ON-ON-(ON) switches...

[RelicHunter1388]

Hello, I cannot understand some things about the SMD capacitors. Can anyone clarify?

In the part list:

7343H C43 22-47uF x 20-25V

C55 22-47uF x 20-25V
C56 22-47uF x 20-25V
C5722-47uF x 20-25V
C58 22-47uF x 20-25V
C59 22-100uF x10-25V
C60 22-47uF x 25V

Does this mean that the capacitors used can be between 22 and 47uF? Is 47uf better?

Capacitor C59 is different (22-100uf) but it is grouped with the others in the same group. Should I go with 100uf?

[kt315]

--------------Voltage
C43 Bottom >= 16V
C55 Bottom >= 16V
C56 Bottom >= 16V
C57 Bottom >= 16V
C58 Bottom >= 16V
C59 Bottom >= 10V
C60 Bottom >= 25V
--------------VALUE
R79 Bottom 18-24Ohm
R80 Bottom 18-24Ohm
---------------------
R81 is absent, do not set it

[kt315]

if you use same size (in mm) tantalum so with lower voltage (10V, not 16) you can set a cap with more value (in uF).
look on the dimensions, not on the values. you can set ANY value, but there is/exist some maximal value for 'fixed' dimentions.
it is.

Does this mean that the capacitors used can be between 22 and 47uF? Is 47uf better?

yup. 2.2 4.7 10 22 33 47. 47uF is better
pls use just SMD tantalums. type 7343H.

[kt315]

especial made topic - please learn it before soldering. https://www.geotech1.com/forums/show...-on-boards-LOL!
also, all tantalums are soldered AT THE END of job, after all.

[kt315]

[2] 2MM (BLUE) = ???

two-sound-disc-mode
https://www.youtube.com/watch?v=W-nM5xZbViQ

[RelicHunter1388]

Thank you for the valuable information!!!

Don't worry, will use the proper 7343H capacitors and 1206 resistors.


All components will be here shortly. I had to order a lot of them because old electronics are almost impossible to find these days. You can find newer ones, but these use modern PCBs with tiny SMD parts. Some components are coming from aboard, so it will take some time until I can start the assembly.


In the meantime, will work on developing schematics for a practical detector frame (stick) and Coils. I think I will go with two Coils. One standard and one small for pinpointing. As a way to give back to the community, all that will be free if anyone is interested.


Specifically, I have in mind something like the small coil in the picture.


But using the tiny coil like the guy in the picture does is impractical. I am thinking of using it with a handle and switching 5-pin cables to connect it to the detector that you can leave around (or you can detach the control box and strap it on your belt or vest). Still conceptualising though. The design must be simple and easy to make and use.

[RelicHunter1388]

Happy New Year to all!!!

I am currently designing the Control Box. I want to have Ground Balance and Notch Width potentiometers adjustable by the user on the field.



That is easy to do with small cables soldered on the PCB, however, potentiometers have three connectors (1, 2, 3), but the PCB has four holes for the trim potentiometers (see picture below). Two of the holes seem to be on the same line, therefore, should these be joined?



Also, since the trim potentiometers are 100K, the normal potentiometers, logically, must also be 100K, but, should they be logarithmic or linear?

[waltr]

Yes, the two holes should be joined on the PCB. The reason there are four holes is to use two different size pots. This is also known as a 'dual footprint' allowing a wider selection of parts.

Linear or Logarithmic depends on the pot's function. Most likely they are linear.

[kt315]

waltr is sure accurate. thank you. use 3 turn pot for GB. '3T pot'.

[waltr]

Yes, a multi-turn pot will make GB adjustment finer.
Good point kt.

[kt315]

JCL does the things very speedy... i hope to get new batch of boards in 2-3 days.

[kt315]

tantalum place pads