Serbian "Most Wanted"

[Pompey]

In RX choose and match all 3 transistors (BC327) with hfe 250-300.
You and Geo have some "switch" in sound? I can not imagine that? What kind of "switching"? It is audio from Fisher 1265/66, it should make pert and shortly "bang" on clear signals. If it is like that than it is ok.
I would like to hear that somehow..

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Hi,Ivconic!I matched all 3 tranzistors in Rx stage with hfe 250 to 300.But for Tx I put with hfe 400.Is too high?I have and with hfe above 500.Isn`t that switches come because of high sensitivity?When no coil connected it starts sound before my GSM start ringing

[ivconic]

In RX choose and match all 3 transistors (BC327) with hfe 250-300.
You and Geo have some "switch" in sound? I can not imagine that? What kind of "switching"? It is audio from Fisher 1265/66, it should make pert and shortly "bang" on clear signals. If it is like that than it is ok.
I would like to hear that somehow..

[Pompey]

Hi,Geo!I can also put BC327 with hfe 250 and see what will happen with amplitude.With 200 ohms trimer I can`t get maximum voltage pp without sinus be a little broken at the top..

[Geo]

Hi,Ivconic!Today I`ll try to increase amplitude of Tx.I don`t know how.I put BC327 with hfe 400,I have 3 kinds of BC327 -with hfe 250 to 300,hfe 400,and hfe above 500.They gave me from the shop 3 different kinds.I bought 40 pieces -they cost only 0.03 euro for 1 piece. I was looking for LF347 and there wasn`t any ,but I ordered some pieces of them.Yesterday when I was looking at some old pcb`s from tv`s,videos ...I spotted "KF347" -super..It`s just LF347 made by Semiconductor The Ic`s are two -enought to put them on the pcb today,but that will happen after 7-8 hours.Now I`m going to work.I want to ask you for the treshold.Must the treshold work without Tx too?My treshold looks like not always work like it should.And sound switches like Geo said.Sound is not flat but sounds like waves without Tx connected.I had not 4,7k pot for sensitivity,so I put 220ohms there -rezistor.This switches may be rezults from high sensitivity,I will put 4,7k pot today to set low sensitivity and try again.These points "max" on the pcb near bias -should they connected together for max volume?

Hi.
At oscillator I use a BC327 with hfe of 255 and i have a good sinus waveform of about 20Vp-p. Generaly your sound is not good as mine, no good TrsHold, no good volume etc. Next week i will try to find the problem
Regards

[Pompey]

Hi,Ivconic!Today I`ll try to increase amplitude of Tx.I don`t know how.I put BC327 with hfe 400,I have 3 kinds of BC327 -with hfe 250 to 300,hfe 400,and hfe above 500.They gave me from the shop 3 different kinds.I bought 40 pieces -they cost only 0.03 euro for 1 piece. I was looking for LF347 and there wasn`t any ,but I ordered some pieces of them.Yesterday when I was looking at some old pcb`s from tv`s,videos ...I spotted "KF347" -super..It`s just LF347 made by Semiconductor The Ic`s are two -enought to put them on the pcb today,but that will happen after 7-8 hours.Now I`m going to work.I want to ask you for the treshold.Must the treshold work without Tx too?My treshold looks like not always work like it should.And sound switches like Geo said.Sound is not flat but sounds like waves without Tx connected.I had not 4,7k pot for sensitivity,so I put 220ohms there -rezistor.This switches may be rezults from high sensitivity,I will put 4,7k pot today to set low sensitivity and try again.These points "max" on the pcb near bias -should they connected together for max volume?

[ivconic]

Ah yes! One more thing;
although Musketeer coils are designed to work well at 5kHz , i also experienced excellent performances between 6 and 8kHz with SMW.
Funny but true!?
So....your 7kHz are just fine. I wouldn't try to change it for now..

[ivconic]

Hi,Ivconic!I just made your last pcb and I tried it with a DD Exelerator II coil 45sm. diameter. Without any adjustments it gives about 30sm for 1 euro. Frequency is 7,05 khz.Do you know what must I adjust for this coil?Tx cap , Rx cap,phase..? Tx gives only 12V pp

Only 12vpp ?? Should be 20-22vpp!
...
DD 45cm !!! Huge coil! I had same last summer and sold it. I had that coil along with 25,32,36 and 18cm for Musketeer. And i compared all those coils. Actually; such huge coil will not "see" coin much more deeper than 25cm coil. But certainly will "see" much more deeper larger items.
So..do not expect enormous depths on single coin with such coil. However..i think it should "see" single coin at least to 45-55cm in air.
...
First you try to rise amplitude, than we will see what else..

Regards!

[Pompey]

Hi,Ivconic!I just made your last pcb and I tried it with a DD Exelerator II coil 45sm. diameter. Without any adjustments it gives about 30sm for 1 euro. Frequency is 7,05 khz.Do you know what must I adjust for this coil?Tx cap , Rx cap,phase..? Tx gives only 12V pp

[Geo]

I let it at the corner.
Saturday i will go to Albania (Tirana) for 5..6 days and when i will come back with fresh mind (Albanian ) i will check it again.

[ivconic]

Yes RX stage.
But now when you said that you put common elco there i don't think it causes problem you explained.
Tantalums from old scraped pcbs can cause simillar problems. New tantalums are ok.
Hmmm...what else could cause such problem?
You must check again all the components and values...hard to guess.

[Geo]

Geo check that tantalum capacitor! C2,33uF at TX stage.

You mean at Rx stage???
I have a electrolytic capacitor because i did not found at local shop tantalium capacitor. It is connected right, except if it is fault.
Yes... it is good idea to replace it

Thank you

[ivconic]

All are good, but..... There is a BIG mistake
When i turn the detector on and for 4..5 minutes it works perfect. After it the sound is switching and the detection distance does to half.
Voltage remain the same (+-4.64). But after it, when i turn it off, it need at least 1 hour to stay off, so when i return it on to work good.
I will check it again.

Regards

Geo check that tantalum capacitor! C2,33uF at TX stage.

[ivconic]

All are good, but..... There is a BIG mistake
When i turn the detector on and for 4..5 minutes it works perfect. After it the sound is switching and the detection distance does to half.
Voltage remain the same (+-4.64). But after it, when i turn it off, it need at least 1 hour to stay off, so when i return it on to work good.
I will check it again.

Regards

Funny and strange!?
Maybe you put some bad component?

[Geo]

All are good, but..... There is a BIG mistake
When i turn the detector on and for 4..5 minutes it works perfect. After it the sound is switching and the detection distance does to half.
Voltage remain the same (+-4.64). But after it, when i turn it off, it need at least 1 hour to stay off, so when i return it on to work good.
I will check it again.

Regards

[nakky]

I made the last version with LM393, but something is wrong, it is the worst sound that i never hear. Only differences are for the MPSA13 transistors, i put BC517 and for BD180 i put BD140 but i believe that are similar on their details. Also with Geb i had not the ability to reject a ferrite rod, maybe thedisk was at very wrong position. Today i will check all

Maybe BC 517 in wrong position??? turn it 180 deg .

Grt Nakky