Just started MPP project

[multieagle]

Silverdog MPP "C" kit.

Purchased this in November, and just getting around to working on the board.

In checking the parts I notice U8 (TL062) & U9 (TL061) differ from the parts list. In the kit there is a TL071 & 72. I assume that is not a problem. There was one 79L05 missing, but I had a couple on hand.

Regarding PL1 and others. If I use the supplied 3-prong connectors, should the back panel face out, or in? Or does it matter? I'm thinking of polarity when connecting power cables.

TIA

[Silver Dollar]

Here's my Mini;


I ordered SMT 4538's so my mini is a mini mini;


The TL071 + 72's are better versions of the 61 + 62's so they are fine.
Not sure about the connectors. I bought a bare board and purchased parts...

[multieagle]

Neat!

[Qiaozhi]

Regarding PL1 and others. If I use the supplied 3-prong connectors, should the back panel face out, or in? Or does it matter? I'm thinking of polarity when connecting power cables.

The connectors are designed to fit either way round. The outer pins are electrically connected, so it won't blow anything up if you plug it in backwards.
The only one that makes a difference is the Threshold (Audio) pot. In that case, the threshold will either increase or decrease depending which way round you connect the plug.

[multieagle]

Well,made it past Step 1. I'm getting -5v . . . well, -4.9v my battery is a bit low. Thanks for the tips. Think I will bask in a successful first step overnight. Tomorrow will do Step 2. I have a tendency to rush ahead without, ahem, thinking. The manual is great, as it forces one to crawl along.

[Silver Dollar]

I built a Davor GEB PCB for my mini;


They plug in via 5 pins so can be swapped out easily;

[multieagle]

I built a Davor GEB PCB for my mini;
[ATTACH]32178[/ATTACH]

What is a Davor GEB?

They plug in via 5 pins so can be swapped out easily;
[ATTACH]32179[/ATTACH]

Also, how do the resistors on your board act across the IC holders?

TIA

[multieagle]

I note the kit uF capacitors are mini-sized (except for the 1000uF). Does size matter (smile)? I had read on another forum that smaller components may not be as durable, more suscepable to failure?

[Silver Dollar]

Also, how do the resistors on your board act across the IC holders?

? Not sure the question. I soldered the SMT IC's to an adapter board and soldered the parts to pads on those boards.
A few parts are "flying" I solidify those with Tack Pac so they do not break during handling.

Small components can be just as reliable but if you are experimenting a lot they are a bit more fragile. Everything is made with
tiny parts these days. Flying parts are susceptible to breaking if you grab the board wrong. Flexing the pcb can crack components.
But build it and pop it in a case and it's just as reliable as anything out there...

[Qiaozhi]

I built a Davor GEB PCB for my mini;
[ATTACH]32178[/ATTACH]

They plug in via 5 pins so can be swapped out easily;
[ATTACH]32179[/ATTACH]

Did it work as advertised? If so, how well did it perform?

[Silver Dollar]

Well I have to finish it up tonight.

[multieagle]

In step 3 it states a 100pf capacitor should be placed under the board between Q2 collector and U2 pin 7. I understand where it is to go, but to which Q2 leg does it connect? Is it the outside leg attached to the trace?

TIA

[multieagle]

Okay, just found the answer: http://www.geotech1.com/forums/attac...5&d=1413800548

[multieagle]

Finished Step 3 and tested okay.

[multieagle]

I have finished to Step 5, and must now wait for missing parts. I had some problems with terminology and processes. For one thing, did not realize a coil must be attached at Step 4. I am using two coils made for the Surf PI, both are copper tape shielded and work well on the Surf. 3 coils are around 300uH, 1 coil 278uH and 1.2 - 1.6Ω. However, I'm getting a reading of 1.5v at TP3 on my multimeter and that does not change with popcan or other metal. On my osiloscope, I'm getting an average 1.10v and that also does not change in the presence of metal. I may have to construct another unshielded coil for test purposes?? See attached image.