Delay control question on SM PRO

[Darin]

I have a SM PRO assembled board I got on ebay, I did not build. I have tried a 4" mono coil I wound and a 8" mono coil I wound. With the 4" coil I can pick up a US nickel up to 7", US quarter the same. Changing to the 8" mono coil gives the same results. These results are with the delay turned all the way counter clockwise. If I turn the delay clockwise signals fades away fast, at about half way on the delay pot I get the same sound as if I place a metal object next to the coil and it overloads. What should I start looking at first so I get full range of my delay pot ?

My coils are made as followed, I used .50mm solid copper phone wire to learn with I know it is not as good as Teflon coated but it is what I had laying around.
Inductance is from coil calculator I do not have a inductance meter yet.

4" mono coil 35 turns of .50 wire inductance .255 mH

8" mono coil 23 turns of .50 wire inductance .292 mH

I have wound two basket coils but have not been able to test them yet, maybe I can tomorrow and see how they work. They are a 4" and a 7" using the same wire.

[sinclairuser]

that wire while not making the fastest coils should work, i have wound mono's out of loads of different types of wire, .50mm single strand should make an ok testing coil.
you need to know which schematic its built from, and check everything, one wrong resistor or cap in backwards can shaft it.
if you are in the UK go to B+Q they are selling multimeters for 29.99 and have everything you could need, ac, dc, ohms, capacitance, inductance the whole shebang, not like those crappy meters of ebay, by a couple of decimals.
you need to test its the only way.

[Darin]

I am in the US, I have looked local but have not found a multimeter with capacitance and inductance on it. No one seams to know what I am asking for either.
I tried the basket coils tonight. The 7" coil picks up a US quarter around 8 1/2" a US nickel just under 8". The 4" coil is around 6" on the quarter and 5 1/4" on the nickel.
They only work with the delay turn all counter clock wise as well.
With all my coils sounding like it goes in overload when the delay is adjusted could this be my coils causing the problem?

I have the SMP3 assembled board from ebay Tocoma56 sells.

I have printed the schematic and the layout that came on the cd with my SMP3 board. I know very little about electronics but am trying to learn how to read them. That is the main reason I bought a assembled board first to try learn about them before building one.

[eagle52]

I bought same board and as per instruction you adjust your delay on the board until you get the best depth and than use your delay pot to adjust further , if your coils are not exactly the same you have to adjust delay on the board every time you change coil

[Darin]

eagle 52 do you have full range of your delay pot?
I adjust R10 to 0 volts for each coil and adjust R2 to see where the depth range is. So far arond 2.7 to 2.8.


I took the board out of the box and checked all of the resitors with my multimeter by going down the parts list to make sure everthing matched up.

I found R11 reads 12.5K my parts list is a 22K metal film 1%.
From looking at the schematic R11 is conected to R10 100K trimmer offset, not sure how this would effect anything. I do set R 10 to 0 volts per instruction.


I do not have a capacitor meter so i did a visual check of the capcitors by matching them to the parts list. All matched and in the right place.
I do not know about the diodes yet I will do a search as how to check them on the board later today.

I checked all other parts such as the TLC555, NE5534, LM358, CD4093, 78L05, ICL7660, CD4066 all matched acording to the parts list and in the correct place.

Thanks for the help

[eagle52]

I have several coils and only basket type coil allows full delay pot adjustment any other coils need slight R2 adjustment to get best performance I think your board is fine ( I do not have tools to measure capacitance of my coils so I am not able to give you any specs)

[Darin]

Thanks eagle52, I am looking for a capacitance / inductance meter, may just have to order one from ebay. I want to get some telflon coated wire to try and make some coils with it, that should help me out.