Everday electronics (EPE)

[satdaveuk]

Hi
Anyone here got the EPE, mags pre volume 11-12 1998 in PDF format, they started in the early 70s which at one time I had all of them from the 1st issue but since 12 years ago bined them due to change of workshops/lack of space, now im gutted.

In return if theres any projects you need the mags for got from 11-12-1998 through to the latest issue on PDF format incl index.

Thanks in advance

Regards

[Carl-NC]

Dave, can you tell me the author of "Poor Man's Metal Locator" from June '06? I don't need a copy of the article, I have the magazine but it's in storage.

[satdaveuk]

Dave, can you tell me the author of "Poor Man's Metal Locator" from June '06? I don't need a copy of the article, I have the magazine but it's in storage.

Hi Carl
Strange that because it was about this project that was my very first post on here, I built it but wanted to do away with the variable capacitor and use a pot.

Anyway Thomas Scarborough was the author and produced by Silicon chip magazine.

Regards

[Carl-NC]

Apparently also published in EPE. Thanks!

[Qiaozhi]

Hi Carl
Strange that because it was about this project that was my very first post on here, I built it but wanted to do away with the variable capacitor and use a pot.

Anyway Thomas Scarborough was the author and produced by Silicon chip magazine.

Regards

Yes - I can confirm that it was Thomas Scarborough.
The design consists of just five components – a TL074CN, a variable capacitor, two search coils (OO configuration) and a crystal earpiece. It oscillates at around 260kHz without a Faraday shield, but the addition of a shield lowers the frequency to half that. The variable cap is used to achieve correct coil balance.

[satdaveuk]

Yes - I can confirm that it was Thomas Scarborough.
The design consists of just five components – a TL074CN, a variable capacitor, two search coils (OO configuration) and a crystal earpiece. It oscillates at around 260kHz without a Faraday shield, but the addition of a shield lowers the frequency to half that. The variable cap is used to achieve correct coil balance.

Hi Carl and Qiaozhi
I still got it in my junk box, they do work but oviously very limited as exspected Skippy told me to try using varicap diodes and a pot instead of the 100pf cap, but I lost interest in it, worth the build at the time to try and get my young daughter interested in electronics.
When i got time im going to put together the one in Febuary this years EPE, but shall use two TLC555, Thomas says with a double 4" 70 turns 30gauge coil he was getting 180mm, which isnt bad considering only 10 components are used.
It does make me wonder that if you can get that out of 1-2 timer chips, why are we not getting alot more with the projects we are building, we seem to be using a hell of alot of components just to get that little bit more.
I noticed in Jan edition they showed circuit of a earth magnetmeter which they called LCR beatbalance and by all accounts it performs quite well.

Maybe we should all look more into Beat balance theory, because apart from these two plus I think Elkta did one, but they proberly only played with the idea.


Anyway its food for thought and im thinking already.

Regards

[Qiaozhi]

It does make me wonder that if you can get that out of 1-2 timer chips, why are we not getting alot more with the projects we are building, we seem to be using a hell of alot of components just to get that little bit more.

Unfortunately it's that thing called "The Law of Diminishing Returns".

Remember - the search coil acts like a transformer. Therefore the EM field energy will fall off at a rate of 1/d^3, and any signal returned from the target will be twice that (i.e. 1/64). The bottom line is that you have to use a lot of clever techniques (equating to [usually] a lot more components) just to gain a few centimetres extra depth.