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**Qiaozhi** · 02-25-2016, 09:05 AM

Originally posted by Cadmaster375 View Post

I have some questions on the specifications and rating of components. I am trying to figure out pricing and such and having some frustrations.

1) temp rating: is lowest OK or should I choose one that is -20c to 120c (approximatly)
2) capacitor rating, form and material I am assuming polyproplene/polyester material since none is given.
3) strange numbers 2n2, 470r, 3r3 I assume 2200F, 470Ω and 3300Ω
4) from factor of IC's pdip? I want to use through board and chip sockets
5) diodes 500mW High Speed Switching Diode (general purpose)?
6) a) Reject (sample delay) pot 100k LIN
b) Audio (threshold) pot 250k LIN
c) R06 resistor 100k multiturn preset
7) any other things I may not know about?

Unless you're planning to detect in arctic like conditions I wouldn't worry too much about the temperature rating. The MPP is designed to use generic components wherever possible, and nothing is really that critical in the design.

To limit the number of different components kept in stock, I generally use MFR4 1% resistors (even if a 10% tolerance would be ok) and ceramic multilayer capacitors.

2n2, 470R, 3R3 are not strange numbers. This notation is known as the component marking standard. So, instead of writing 4.7k (for example), you write 4k7, thus removing the 'dot' (which can often get lost) resulting in a 47k resistor being fitted by mistake. In this case, 2n2 = 2.2nF, 470R = 470Ω, 3R3 = 3.3Ω. Basically, any number to the right of the symbol is considered to come after the decimal point.

All the ICs are standard DIL packages.

Everything else is fairly obvious.

**green** · 02-25-2016, 02:18 PM

Originally posted by Qiaozhi View Post

Unless you're planning to detect in arctic like conditions I wouldn't worry too much about the temperature rating. The MPP is designed to use generic components wherever possible, and nothing is really that critical in the design.

To limit the number of different components kept in stock, I generally use MFR4 1% resistors (even if a 10% tolerance would be ok) and ceramic multilayer capacitors.

2n2, 470R, 3R3 are not strange numbers. This notation is known as the component marking standard. So, instead of writing 4.7k (for example), you write 4k7, thus removing the 'dot' (which can often get lost) resulting in a 47k resistor being fitted by mistake. In this case, 2n2 = 2.2nF, 470R = 470Ω, 3R3 = 3.3Ω. Basically, any number to the right of the symbol is considered to come after the decimal point.

All the ICs are standard DIL packages.

Everything else is fairly obvious.

Temperature coefficient for the ceramic multilayer capacitors? Make sure they are big enough to see. I ordered a selection awhile back and had to reorder a few sizes because they were to small for me to work with.

**eclipse** · 02-25-2016, 02:51 PM

Grab few more damping resistor values, if you are making an order make sure you buy few more values just in case.
Ex: 470, 430, 520
You can use 1 pot with switch (on/off) to save panel space.

**LukeJ** · 02-25-2016, 05:47 PM

While I understand the need to save a few bucks here and there....

From personal experience I would highly recommend buying the kit from SilverDog. It was like $51 shipped to my door.

Had everything necessary to construct a working detector module.

In my opinion, well worth the few extra bucks...

Good Luck,

Luke

**leopard70** · 02-25-2016, 09:55 PM

"pot 100K LIN" means potentiometer 100 KILO OHMS LINEAR.There are two types potentiometers-LINEAR and LOGARITHMIC."MRF" means METAL FILM RESISTOR.GOOD LUCK!

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specification of parts list and non standard numbers questions

specification of parts list and non standard numbers questions

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