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\help with Odd Chip

:: EPE Chat Zone ­:: ­Radio Bygones Message Board :: » EPE Forum Archives 2007-2009 » Archive through 14 November, 2007 » \help with Odd Chip « Previous Next »

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poriet
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Username: poriet

Post Number: 221
Registered: 06-2005

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Posted on Tuesday, 30 October, 2007 - 02:58 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Hi,
When I was at the Leicester Radio Fair in September I got some transceivers ( is that the word ? ) sort of transmit & receive boxes the size of car radios. These are ex-Police or Water-Board or somebody. Theres a radio-business in Northampton which aquires these things virtually as scrap and you can get them for pennies. ( If anyone wants their number I'm happy to give them a plug ) These things are real quality gear; old technology, but lots of usefull stuff and a real bargain IMHO.
One of the chips is an 8-DIL type SP8793 and I want to know what it does. It's a divider which can take a signal up to 200MHz and outputs the same waveform divided by either 80 or 81 ( up to the conscience of the individual )
The question is, what on earth does a radio need one for exactly?
P.
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zeitghost
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Username: zeitghost

Post Number: 907
Registered: 01-2006

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Posted on Tuesday, 30 October, 2007 - 03:06 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Frequency synthesiser prescaler.

It divides the Local Oscillator down to a frequency the PLL input can cope with.

The n/n+1 divide ratio lets you get a finer control of frequency.

There's some highly tedious maths that describes this.
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obiwan
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Username: obiwan

Post Number: 1986
Registered: 12-2005

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Posted on Friday, 02 November, 2007 - 02:33 am:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Ditto. PLL's use them a lot. You start with one known stable frequency, and you can synth just about any other frequency with the right dividers. Or you can decode FM with it.
Do Not Hit The Fly That Lands On The Tigers Head.
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electron
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Username: electron

Post Number: 10
Registered: 08-2007

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Posted on Saturday, 10 November, 2007 - 05:20 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Re ADE7756AN chip.
Many thanks to John Becker for publishing my e-mail offer in the December issue of EPE magzine.I have already received two enquiries for this device from readers.The effort I put in to obtain these devices is now paying off!
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john_becker
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Username: john_becker

Post Number: 1642
Registered: 05-2005

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Posted on Saturday, 10 November, 2007 - 07:12 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

That's great Electron. Pleased to help. I'll put a note into Readout, probably Feb issue now.

J
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poriet
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Username: poriet

Post Number: 227
Registered: 06-2005

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Posted on Monday, 12 November, 2007 - 10:26 am:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Why is this guy piggy-backing other people's threads?

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