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After much work, this is my final Bandido clone which might also help owners of an original.
All the component references are for my version and do not match Tesoro, but 99% of the circuit is the same. Slight component differences are not improvements or mods, just what I had to hand. I have a separate TUNE switch because I did not have the right one in my stock. All mods are marked. My coil is 'unknown' from Ebay (I got three for £5.00 on a punt). It runs at 13.86KHz.
There could be two problems: 1-Your detector was working okay but now isn't.
2- It never worked (Clone or Original).
In all case the waveforms shown, or reasonably close, are the key. Many times my detector worked really well in air tests yet I still pulled faults from the strip board - mainly tracks not broken. With no coil you are looking for more or less 0v at all the op-amps with a few exceptions as shown. You can ignore everything else until with a coil you can see the waveforms I have sketched. The scope was set to 20usec/div. I figure that if you have a scope and are using it you can easily figure what the waveforms indicate.
If you are building a clone then you really only need a coil, GROUND BAL and DISC pots to check the waveforms. I have never been able to get it to work without the 40M across the AUTO switch.
At first I used an LM358 for the front end but I had to switch to the Tesoro part due to Xover distortion. This can be cured with a hard pull-up but I decided not to do that. Colours (or colors if you are far away) are the ones I used for my connectors.
I decoupled everything with cheapish disc ceramics. All other non- elec caps are monolithic ceramic. I don't know why everybody seems hung up on WIMA -they're nothing special. most resistors are 5% carbon film with a few metal oxide 1% when I couldn't find a value. I have fitted two PP3 batts so I can use cheap Zinc ones and get a good life from them (I picked up a load at a car-boot for 20p each).
One last word of advice - if you make a clone think about the layout - it really does pay. In RF design the general rule is straight lines for signals, the same approach helps here: you do not want wires running all over the board when you are looking at tiny phase shifts.
Testing on my lawn I had a really hard hit. I dug. Nothing. Checked, hard hit. Was it real or is my detector still not working? I dug. "Is that you messing my nice lawn up !", No dear, just fixing Mole damage. Found a small piece of tin.
Some might say it is a bit of old fencing metal but I think it is a piece of an amulet that belonged to a 2nd century princess who used to live here before me.
All the component references are for my version and do not match Tesoro, but 99% of the circuit is the same. Slight component differences are not improvements or mods, just what I had to hand. I have a separate TUNE switch because I did not have the right one in my stock. All mods are marked. My coil is 'unknown' from Ebay (I got three for £5.00 on a punt). It runs at 13.86KHz.
There could be two problems: 1-Your detector was working okay but now isn't.
2- It never worked (Clone or Original).
In all case the waveforms shown, or reasonably close, are the key. Many times my detector worked really well in air tests yet I still pulled faults from the strip board - mainly tracks not broken. With no coil you are looking for more or less 0v at all the op-amps with a few exceptions as shown. You can ignore everything else until with a coil you can see the waveforms I have sketched. The scope was set to 20usec/div. I figure that if you have a scope and are using it you can easily figure what the waveforms indicate.
If you are building a clone then you really only need a coil, GROUND BAL and DISC pots to check the waveforms. I have never been able to get it to work without the 40M across the AUTO switch.
At first I used an LM358 for the front end but I had to switch to the Tesoro part due to Xover distortion. This can be cured with a hard pull-up but I decided not to do that. Colours (or colors if you are far away) are the ones I used for my connectors.
I decoupled everything with cheapish disc ceramics. All other non- elec caps are monolithic ceramic. I don't know why everybody seems hung up on WIMA -they're nothing special. most resistors are 5% carbon film with a few metal oxide 1% when I couldn't find a value. I have fitted two PP3 batts so I can use cheap Zinc ones and get a good life from them (I picked up a load at a car-boot for 20p each).
One last word of advice - if you make a clone think about the layout - it really does pay. In RF design the general rule is straight lines for signals, the same approach helps here: you do not want wires running all over the board when you are looking at tiny phase shifts.
Testing on my lawn I had a really hard hit. I dug. Nothing. Checked, hard hit. Was it real or is my detector still not working? I dug. "Is that you messing my nice lawn up !", No dear, just fixing Mole damage. Found a small piece of tin.
Some might say it is a bit of old fencing metal but I think it is a piece of an amulet that belonged to a 2nd century princess who used to live here before me.
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