What is it?

[bklein]

I got this from a guy at work. Looks like a project from 1964 Popular Electronics or whatever... What do you think it is? Has a control in front for zeroeing the sound and another for volume. Makes noise but doesn't work in my metal engrossing garage. serial number is: 76MMSD486! Jeez, must be thousands of em out there!

Barry

[Qiaozhi]

I got this from a guy at work. Looks like a project from 1964 Popular Electronics or whatever... What do you think it is? Has a control in front for zeroeing the sound and another for volume. Makes noise but doesn't work in my metal engrossing garage.[ATTACH]17283[/ATTACH] serial number is: 76MMSD486! Jeez, must be thousands of em out there!

Barry

I'm not sure, but it might be a Compass Coin Hustler, or similar BFO detector.

[Melbeta]

Excelsior Electronics unit called Myte-Myte

The red one is the Myte-Myte Super Deluxe version...

[bklein]

That's definitely it! Now Googling it seems like there are fond memories of it by many.
It will probably end up on ebay as I have too many detectors already...

Barry

[Melbeta]

Mispelled the name slightly....

That's definitely it! Now Googling it seems like there are fond memories of it by many.
It will probably end up on ebay as I have too many detectors already...

Barry

Just noticed I spelled the name wrong, is Myty Myte, not Myte Myte. Here is a shot that someone posted in past.

[bklein]

I took mine to a park and it doesn't work. There is a point where it goes quiet somewhere in the middle of the adjustment range - but it doesn't respond to a metal/coin presence. Battery check lights the LED.

[Melbeta]

Clean the tuner with TV tuner cleaner...

Sounds to me like you had audio sound, then it went away, so it appears to me that the 10 turn tuner might be dirty inside or defective. The Myty Mite is famous for having bad tuners.

Spray the inside (with the battery unhooked) with TV tuner cleaner spray, let it dry a bit, then try it again.

You had the lid off the unit, so you can tell it is a very very simple TR detector, having a large 500 uF 15V electrolytic, a couple of transistors, a vertical pot, some caps and some resistors. Not much there to repair.

At least the battery check works and lights the LED. Sounds more to me like the tuner is dirty or defective...

Make sure the speaker works. Sometimes when someone plugs earphones in, it shorts out the speaker. But you must have heard some kind of audio sound, before it disappeared?

But the coil might be bad too.... And someone might have noticed it did not work, and fooled with that adjustment trimmer pot inside also... I am not sure on that trimmer pot, it may adjust the null of the coils Tx/Rx. I would say, repair everything around that pot before you play with it, if you play with it. It just might be a parts unit now...

People liked them because they were simplicity at its finest, just one control and off you go. This was before the VLF and discriminators came about. Others have a internal audio pot and a tuner pot for the coils, and an adjustment trimmer pot to adjust the gain of the base of the transistor to the Tx coil.

Now, I do not know if this is a mineral/metal unit, if so, then the tuner can go to a point inbetween the mineral side and the metal side. Then it goes quiet, which we call "the null position". If you turn the tuner back, see if it responds to a coin. If not, hold some black sand to the coil, if it goes loud, then it has an mineral/metal tuner, which was also common on the old 10 turn tuners...
Melbeta

[bklein]

Could you give me some clues as to what I should see with a scope on this puppy?
I tried temporarily replacing the 470uf cap with no change. Transistors are 2n3565 (3), 2n4250, and pn3638. They don't appear to be shorted - maybe low gain though with my in-circuit tester. The coil housing is sealed - if there is anything to tweak in there it would be a major effort to get at it. I adjust the pot from silence to when it makes a tone, then move the coil towards some serious steel and the pitch starts to move up in frequency some when the coil is like 1-2" from the steel.

[Melbeta]

No scope wave forms...

Could you give me some clues as to what I should see with a scope on this puppy?
I tried temporarily replacing the 470uf cap with no change. Transistors are 2n3565 (3), 2n4250, and pn3638. They don't appear to be shorted - maybe low gain though with my in-circuit tester. The coil housing is sealed - if there is anything to tweak in there it would be a major effort to get at it. I adjust the pot from silence to when it makes a tone, then move the coil towards some serious steel and the pitch starts to move up in frequency some when the coil is like 1-2" from the steel.

I cannot help you on any scope stuff. I have no wave form information. I had a friend who fooled with it, along with another guy in the past, who used to repair the little buggers. That is why I know a bit about the detector, although I have never seen one, nor had one in my physical possesson. I spent my time with Compass detectors at that time period. My friends played with them and other early detectors. IT kind of sounds more and more to me, that it is working, at least working somewhat. It is not a powerful unit though, it is a simple detector.

The detector is NOT a VLF detector, nor is it a Discriminator detector, it is prior to that time. I have seen an old field test of the unit in magazines, saw it recently in one, but I am not sure which magazine right now that I spotted it in.

This is what I think you have:
I really suspect that the 10-turn trimmer pot is a tuner that tunes between the null position (center location between mineral and metal sides), if you turn it to the left beyond the null position, the detector will be operating in the mineral detection, and will see black magnetite sand. In this position it will give a "positive" sound when it sees magnetite black sand, but go quiet (negative sound) over metal objects. Now this is my guess, I am not positive it is a metal/mineral detection unit. Just a guess based 100% on the fact it has a 10 turn tuner pot!

In other words: MINERAL SIDE --> Null center <--METAL SIDE

You need to find the (CENTER) quiet place, which is the null. Your unit may not be defective at all, and you just might not have it tuned correctly!!!

If you turn it toward the left side, of the null location, sound should come back in again. Then turn it back into the null (it should go quiet then) and then turn it to the right side, of the null position, and sound should come back again. I am not positive, but I believe this is what you have. Why else would they have a 10-turn tuner?

In the Mineral side, it will respond positively to black sand, in the Metal side it will respond positively to metal objects. I think this is what the Mity Mite detector might be.

The early models did not have 5 transistors, only the later and last models had that many transistors, before the detector company went out of business. I have a photo of the inside of the early models, and that is what I was speaking of, from that photo. I am going to post his photo here, I think he would not mind. I believe his is a earlier model then your model, as you can see, it does not look like it has many parts on the board.

The coming of the VLF detector, which tuned out the black sands, killed the sales of this simple detector. Then the coming of discrimination modes, finished it off for good.

The very last models had a pot for separate volume control. Not sure you have that on your model as I do not see any other pot on the top of the case other then an on/off switch.

IT is my guess however, that the 10 turn pot adjusts between a mineral and metal side, but I am not absolutely positive. I have reverse engineered a lot of old detectors, and would like to reverse engineer this one, but I have not run across one here locally.

You could say the Mity Mite apparently was a hot operating little light weight TR detector, that people loved for its weight, for its time period. It could be good to find black sands in a stream or a bank, then sluice it to see if there is any gold in the stream or bank... That is what they used to use the Mineral/Metal detectors for.
Melbeta

[Melbeta]

More Mity Mite information...

Fournd the field test, it was done in 1976, apparently the detector came out around 1972 or 1973. The field test and Mity Mite's adv in the magazine does not mention any mineral/metal tuning, so that will be your discovery I guess.

It says it is an TR detector, does not have discrimination, and is not a VLF detector. The pot sticking out the front is a 10 turn pot.
Melbeta

[Qiaozhi]

Myty-Myte Schematic

I found this in my archive.

[bklein]

So would everything on the schematic left of Q2 be inside the coil housing? I'd expect to see a relatively fixed amplitude RX signal that would get larger in amplitude as the target gets closer to the coil.

So, given I have a bunch of better detectors, eventually I will sell this one. Should I do whatever is necessary to try and fix it or do collectors want it original and I shouldn't spend the time?

[bklein]

I tested both electrolytics with a LC-102 and replaced one just because.
I removed all transistors and tested them with my M3 tester.
No issues.
So I opened the coil up - and found nothing obvious wrong.
I tested the transistor and it was good too.
So I'm at a loss on this one... no clue.

[Joe(TX)]

...SIMILAR TO THE COMPASS COIN HUSTLER....

...BKLEIN...there is a good possibility that you just have it tuned wrong....but Not being there it is very hard to say...since you have little interest in it...I would Not repair it just offer it on Ebay as a Parts Detector......you should get at least $20.00 or more for it.....also offer it on the Compass Detector Forum and the Vintage Detector Forum for Sale...those members are more likely to respond than the average Metal Detector Forum.....Merry Christmas Joe