electronics part question

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susan007

Joined Jun 26, 2013
8
Hello,

I have a schematic of an AM transmitter and want to know what inductor it is using and how it is selected. attached is the ckt schematic.

In general how does electronic designer identify which part is being used. In schematics only values of inductor, capacitors and resistors are provided. But there are many types of those. for eg, in the schematics it shows 200uH inductor but there are many inductors with this value, surface mount, ferrite beads etc.

many thanks
 

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MrChips

Joined Oct 2, 2009
26,151
This is not an AM transmitter. It is an AM receiver or radio.
The coil and capacitor constitutes a resonant LC circuit tuned to the radio frequency you wish to detect, usually in the AM MW band, 560kHz to 1600kHz.

The coil is air wound. You can make this on your own by winding about 80 turns of enameled copper wire on a toilet paper cardboard tube.

You can learn more by checking any site on how to make a crystal radio.

How does a designer know what type of component to use?
By experience and reading up in places like All About Circuits.
 

WBahn

Joined Mar 31, 2012
26,398
In general how does electronic designer identify which part is being used. In schematics only values of inductor, capacitors and resistors are provided. But there are many types of those. for eg, in the schematics it shows 200uH inductor but there are many inductors with this value, surface mount, ferrite beads etc.

many thanks
The key thing to keep in mind is that the electronic designer isn't looking at a schematic and having to figure out which part is shown -- they are the person deciding which part will be shown on the schematic!

The piece of the puzzle you are missing is the BOM -- Bill of Materials. There is no reasonable way to print all of the relevant information about each component on the schematic. Instead, each item on the schematic is cross-referenced via it's reference designator, to an entry in the BOM. While there is no universal format for a BOM, usually the intent is for it to provide sufficient information, either directly or through references to other sources, to place an order for the part or at least to be able to find a suitable substitute.

The schematic is intended primarily to provide a high level functional view of the circuit.
 
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