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Amplificaiton R&D

Harry Munday edited this page Sep 10, 2024 · 11 revisions

Amplification R&D

This document has notes on amplifier development and a list of off-shelf amps in testing and available to buy and other misc notes.

This doc is mostly related to the improvement of the CX Cards SNR or signal-to-noise ratio.

Standardised Boards

ADA4857

Tip

Do not use PCBway for less then 5 unit orders, you will pay 3 times more then KoFi for a single built amplifyer.

Order Links: ADA4857 KoFi / ADA4857 PCBway

Developed by Rene Wolf as a second generation, "adjust per unit" impedence matched amplifier board based around using two ADA4857 aplifyer ICs with 0805 pads for gain/input termination so requires an assortment resistor book and a entry to mid range benchtop type digital store oscilloscope.

Full name vhs-rf-amp-ada4857 ADA4857 GitLab Repo.

Analogue Devices AD8367

The most commonly deployed off-shelf RMS amplifier considered the go-to for HiFi/Video FM from tape and laserdisc formats, using 0603 parts it can be user modified if required.

AliExpress

vhs-rf-amp-sgm8302

GitLab Repo

Rene Wolf's first generation amplifier for due duel channel capture using the sgm8302 amplifier IC.

Analog Devices Dual Channel OPA AD605

An off shelf board that is widely available on AliExpress.

Texas Instruments OPA657

(Confirmed on LD players)

Texas Instruments OPA690

Used by the DomesDayDuplicator

Notes

Note: Testing list

AD605

https://www.aliexpress.com/item/AD605-VGA-Dual-Channel-Voltage-module-Control-Adjustable-Gain-Amplifier-Module-Low-Noise-High-Precision-5V/33026097817.html 23GBP with VAT

The way the board is supplied, the 2 channels aren't configured the same.

Absolute gain range programmable −14 dB to +34 dB (FBK shorted to OUT) through 0 dB to 48 dB (FBK open)

One channel has FBK shorted to OUT (-14 to +34) gain range, and the other channel has FBK open (0 to 48db) range, controlled by R5 and R6.

OPA690

Used by the DomesDayDuplicator

https://www.aliexpress.com/item/33008732817.html

OPA657 - In testing

https://www.aliexpress.com/item/32790115607.html

LT1252

Analog Devices Linear Technology LT1252 Low-Cost Video Amplifier (built for application used by CubeTec's BetaCam add-in boards for example)

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