AVR+DSS Frequency Mod SD2100V2

[sinclairuser]

someone mentioned meteorites being radioactive, if it worries you you could build or buy a geiger counter to check them.
though i dont know know if they emit alpha,beta or gamma.

[IBGold]

The resistor to be changed to allow the SD2000 to run as noted on the board layout below sorry for the delay.

Regards, Ian.

[nalbeki]

Jiminy,

For the Modifications for the 2000 go to Ismael's site Minelabmods.com he has all the mods there well documented that you can download I will send you a PM with a picture of which resistor to remove I have mine switched and only switch it out when using frequencies below 1.25 MHz, I would think Mario's device would plug in on the center pin of the jumper-pins where you select which standard crystal you use and earth the same place as a multi crystal switch is connected and is explained in the 2000 mods this is the same as where my VCO is connected.

What are the symptoms of your 2000 what does it do or not do?

Regards, Ian.

Hi Ian, I want to learn too which resistor should be removed to run SD2000 below 1.25 Mhz. Can you send me the picture too.

[nalbeki]

Hi Ian, I want to know which resistor should be removed to run SD2000 below 1.25 mhz. Could you send me a picture? I can't send you pm.

[GoldenKiwi]

Hi Mario, all - If I understand it correctly this approach provides the ability to vary the clock frequency and scales all timing with fixed ratios. Is that correct?
Did it scale any timing non linearly? Ie the sample delays?
Cheers!

[townend66]

Hi Mario. I was just wondering if you sell kits for this project?

[mario]

Got the 100mhz crystals today and popped it in my dds unit. It now works fantastic, the machine operates right down to 1.1mhz with no problem. I just love how you can fine tune it and find a stable frequency. Nice work Mario. Will put a short video on youtube soon.

You can thank Mick and Ian for that. Personally, I didn't know SD2000s could be stable at those frequencies because I don't have one to test.

I'm glad the mod worked out for you.

Let me know if you decide to make the print files public so that I may include them on my package.

[Finderskeepers]

Got the 100mhz crystals today and popped it in my dds unit. It now works fantastic, the machine operates right down to 1.1mhz with no problem. I just love how you can fine tune it and find a stable frequency. Nice work Mario. Will put a short video on youtube soon.

[mario]

Hi Mario

Those 100mhz are hard to find, but last night I hopped onto Element 14 which had 26 left in stock and ordered two. Should receive them later next week. Got my unit working, but it should work properly when I get that crystal replaced. I built this signal generator so it would operate at lower frequencies and now I have a substantial increase in detection depth.
This detector does not operated well in the suburbs, so to test it properly I will have to go out of the city.
I hate working with smd parts but I am happy that the ad9851 mounted well. I have posted a few photos of my unit.
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Glad to hear it working.

I intentionally used smd parts to keep the board small. Also, you'll be surprised at the number of parts manufacturers keep from DIP packaging. Even SMD is becoming increasingly rare these days, with some companies preferring others like QFN (yikes!).

Once, you get that 100Mhz Osc, you should access the full range of frequencies intended for your SD2000.

Mario, ever get your detector working? Remember back a while ago that it quit.

Haven't heard or seen much of you over the past year.

Hopefully you and yours are all doing well.

Oh I'm still in the modding seen, just modding different equipment.

You could check some of my public stuff at thingiverse.

Shortly after frying my metal detector, we bought an old house.

Needless to say, I needed new toys to make the much needed repairs.

So, in other words, I find myself these days spending more time with my router table and miter saw than my metal detector, which I never did fix (One thing lead to another, and I found myself caught up on my woodworking hobby. So out of sight out of mind for my poor SD2100).

Like I said before, it's still always good to see some interest in this project. I'm glad people were able to benefit from it, even if there were only few.

[Jiminy]

Mario, ever get your detector working? Remember back a while ago that it quit.

Haven't heard or seen much of you over the past year.

Hopefully you and yours are all doing well.

[Finderskeepers]

Hi Mario

Those 100mhz are hard to find, but last night I hopped onto Element 14 which had 26 left in stock and ordered two. Should receive them later next week. Got my unit working, but it should work properly when I get that crystal replaced. I built this signal generator so it would operate at lower frequencies and now I have a substantial increase in detection depth.
This detector does not operated well in the suburbs, so to test it properly I will have to go out of the city.
I hate working with smd parts but I am happy that the ad9851 mounted well. I have posted a few photos of my unit.

[mario]

Hi Ian, good to see you're ok.

Stateside, these detectors are increasingly being used for meteorites because they go deep. I found some nice gems back in the day and have thought about making them into jewelry. But I hear some are radioactive though, so maybe I shoudln't ... the thought of giving someone a bad case of melanoma is not my idea of a good gift...

I got your message, Finders.

Oscillator speed does matter in terms of signal integrity, so I would still look for a 100Mhz Oscillator. I experimented with 30 Mhz before settling on 100Mhz and noticed some drift. You could modify the Hex easily to change the multiplyer, but why do so considering the drift issue?

I still have boards (and parts) left, so you could have ordered them from me. I thought $15 for the board was reasonable considering the amount of time I spent on the project.

I thought this project was dead, so it's nice to see that there's still interest. Maybe I should post it on my google account to increase availability now that geotech has gone private?

Can you post some pictures?

[IBGold]

Yes with this Mod and cleaning up the +5V/-5V powersupply and improving the DC filtering of the IC's makes a big difference although my unit has been radically modified I am very attached to my old girl would not get rid of it for anything even though it only gets used intermitantly these days.

Regards, Ian.

[Finderskeepers]

Thanks for that Ian, this must be the ultimate mod for the 2000/2100's. I hope to get it working by next weekend. Got the board etched today and soldered the vias. Still waiting for parts to arrive, was unable to order the 100mhz crystal so i got a 50mhz instead. I noticed in an earlier post that it should run ok with a 30mhz crystal.

[IBGold]

Correct mine using Mario's board has been running faultlessly for at least two years now thanks to Mario's skills.

Regards, Ian.