Beachmaster Files

[Olly]

Actually, the coil I used for testing was closer to 9", so 22.5 cm diameter not 20 cm.

[Made me 2023]

merci bcp

cordialement

[Qiaozhi]

merci bcp

cordialement

Please make your posts in English.
Thanks.

[hamedtaran]

Oops! My mistake...
My original design used a 5K pot, but then during testing I found that 20K gave better results so I updated the schematic but inadvertently forgot to update the BOM as well - I do apologise. I will update the BOM when I release the updated doc pack.

Pinpointing is only meant to be used for short periods of time (5 seconds or so at a time). When the pushbutton is pressed it stops updating the SAT level and holds it for a while allowing you to move over the target a lot slower in order to pinpoint the location. Unfortunately this level does leak away so pinpointing can't be used continuously in order to turn the detector into a non-motion type.

I have had a look at your video and it does seem to be working more or less correctly - I can't quite figure out the detection distance of the coin you are using but it looks reasonable. I found that with a 300uH, 20cm, shielded, bundle-wound coil and a TX width of 50uSec I was just about able to detect a 1Euro coin at 12" when the threshold was set low (more clockwise) in a low noise environment.

Kind regards

Hi

[hamedtaran]

Hello, As you remember, I made this circuit about 2 years ago.
The volume of my circuit is very low, what should I do?
I want to use a small 8 ohm speaker instead of headphones
Thanks

[Olly]

Hello, As you remember, I made this circuit about 2 years ago.
The volume of my circuit is very low, what should I do?
I want to use a small 8 ohm speaker instead of headphones
Thanks

The circuit is really designed for a 32 ohm headset, but you could try using a 1K pot for POT5 to see whether that helps.

[hamedtaran]

The circuit is really designed for a 32 ohm headset, but you could try using a 1K pot for POT5 to see whether that helps.

I used a jumper instead of pot5, but the volume is still very low
thanks

[Olly]

OK, give me a while to investigate and I'll come back to you if I find a solution.

[hamedtaran]

OK, give me a while to investigate and I'll come back to you if I find a solution.

Thank you for your time

[Olly]

Hello, As you remember, I made this circuit about 2 years ago.
The volume of my circuit is very low, what should I do?
I want to use a small 8 ohm speaker instead of headphones
Thanks

Another way to get more volume is to adjust the Gain trimmer RV5. If this is already trimmed to the max then reducing R39 from 10K down to 4K7 will help, but in this case please adjust RV5 back to center trim first before testing or else Q8 may overheat. It can then be adjusted to suit.

Please check on the temperature of Q8 continually while testing as it will now be subject to greater power dissipation.

Let me know how you get on.

[lxs17757414132]

R43 schematic DNF, can anyone tell me which part to use for installation

[pito]

just add LM386

[Olly]

R43 schematic DNF, can anyone tell me which part to use for installation

For normal use with headphones R43 is not fitted. (DNF = Do Not Fit).
If you wish to drive a small speaker and the audible volume range is all in the final 1/4 turn of the Volume pot, then you can experiment with fitting R43.
I would start with a 1K resistor and see how that goes.

[lxs17757414132]

My project is about to be completed, and my oscilloscope is broken. It will take a few more days to arrive, R2, I saw that you discussed using a 1m5 resistor, as it was not indicated in the schematic diagram. What is the maximum supported coil size of 1 * 1m at the beach dock

[Olly]

My project is about to be completed, and my oscilloscope is broken. It will take a few more days to arrive, R2, I saw that you discussed using a 1m5 resistor, as it was not indicated in the schematic diagram. What is the maximum supported coil size of 1 * 1m at the beach dock

R2 is not normally fitted, but you can use it to fine-tune the frequency when POT1 is in its center position if you wish.
The system doesn't care what physical size your coil is, just keep it to somewhere around 300uH to 500uH and it should be fine.

Good luck with the build.