EE Treasure Hunter 40kHz quartz crystal

[John Harris]

Does anyone know of a source in the UK for a 40kHz quartz crystal that was used in the EE Treasure Hunter?

Alternatively could I use the more commonly available 32kHz crystal???

Many Thanks

John Harris

[Seras]

Re: EE Treasure Hunter 40kHz quartz crystal

hi you can uses a cristal of digital clock this is a 32760 Hz. I use this and work well.

[grimpo]

hi i built the ee treasure hunter and used a 40khz crystal but still i get no sound the board looks good but i dont think im getting 16v at the ic's do you know what the pob could be

thanks
chris

[rtuser]

best result

hi

[rtuser]

Best Result

I obtained best result with this conditions:
Crystal: 38KHz (or 32KHz)
Coil: 14 turns of .71mm wire with 38cm diameter.(It improves sensitivity about 40% !) of copurse with a 40cm disc not 20cm.
Input voltage: About 11volt. a voltage regulator recommended.(Use 25 volt capacitor instead 16 volt)
Use 100uF instead 68 and 10uF instead 6.8
IRF840 instead 740
It can detect 10p coin at 28cm depth!
This is my best result. Of course one of my friends who is technical person, improved this sensitivity with additioanal manipulation. That circuit can detect 10p coin at 40cm depth !!!

[mohammad_nos1]

hello rtuser
please send me the schematic which your friend improved and
can detect 10p coin at 40cm depth
[email protected]

[Unregistered]

me also like the diagram

[email protected]

[sayzer]

Schematic for Best Result

Can I also have the same schematic in which you say you had the best result?

Thanks in advance.
[email protected]

[nelson]

Hello rtuser
May i have a copy of your friend schematic which was improved and
can detect 10p coin at 40cm depth. By now i have the standard schematic stuart2 working, but not so good has you posted here.
In advance many thanks.
Nelson
[email protected]

[Carl-NC]

BTW, was looking at crystals in Digi-key & Mouser, both carry 40kHz.

- Carl

[Fred]

I have built this detector, here is a error on the parts list, the two transistors for the "boosted" power supply are inverted.Just check the schematic, it is OK.

Also, i found strange that the 4011 oscillator have its supply only after it start oscillating.This is probably why it takes some time to start working.
I also had to put a 330k resistor between pins 14 and 13 of 4011 ic,or else there was no always output pulses.

if i supply mine with 11V or so, i cannot set it to a no-sound condition.
I used a 32 khz crystal.

Fred.

[Fred]

I know why i needed the 330k resistor:there is a bug on the PCB, pins 12 and 13 of 4011 should be shorted.Then the 330k is not needed .
Fred.

[aiman197]

crestal 40kh

uses a cristal of digital clock my frend

[Radioman]

I also built this circuit with a 40khz crystal,but the circuit seems to be running at 61 kHz any ideas as the board has been checked many times is there a fault on the PCB art work or have they got the wrong component values around the crystal?