# VGA repeater/extender circuit

Apparently noone ever needed anything like this on the internet because I was not able to find any example, so I hope this will become the reference question.

I need to repeat a vga 800x600 signal up to 15 meters away but can't find any decent reference for this. The signal is a CCTV dvr output signal. Commercial VGA repeaters are quite expensive ($160 each) and I'd like to be able to make one on my own. It seems as if it is not that easy but after all it's an analogue signal, is there not any atmegaXXX chip which can repeat an analog signal on its outer pins? All I found was examples of very poor graphic quality like below, very far from being a 800x600 color video! • Sorry to split hair in four diameterwise, but "back in the days" 800x600 was called SVGA :-) – FredP Feb 25 '14 at 20:11 • PS : unfortunately most of the atmega chips do not have DAC (except 328 I think) but anyway they are not well suited to reproduce a precise timing signal like this – FredP Feb 25 '14 at 20:39 • LT6557 in stock Digikey about$5.50/1 cds.linear.com/docs/en/datasheet/6557fa.pdf. 3 channel video amp IC. TSSOP. 400 MHz BW at 2V p-p out and 2200 V/uS :-) . [ Wow ] . – Russell McMahon Feb 25 '14 at 20:56
• Following on Russell's comment.. demo board for that chip is \$50. linear.com/solutions/1943 I think it's a 4-layer board, so not a bad price. – Spehro Pefhany Feb 25 '14 at 22:15
• LT6557 seems to be a good candidate, however it's missing H-sync and V-sync lines! how does one deal with those? why aren't they included in the chip I/O? – dendini Feb 26 '14 at 18:50

Why use a microcontroller just to boost a signal ?

A simple op-amp is just what you need.

Here is the Maxim's page for Amplifiers according to the resolution (SVGA is 800x600 ah FredP said): http://www.maximintegrated.com/products/video/amplifiers.cfm

HSYNC and VSYNC are TTL signals so a small buffer is sufficient.

VGA Electrical FAQ

• Forgotten Electronics!!! – GR Tech Feb 25 '14 at 20:58
• what is the BW (MHz) inside the chip characteristics? 85Mhz 230MHz what are they? there's no explanation on their website. Am I supposed to use one say max4383 for each R, G, B line? – dendini Feb 26 '14 at 19:02

I need to repeat a vga 800x600 signal up to 15 meters

Cable, cable and cable. You can easily find fast drivers (differential or not) but if you haven't considered the cable and how it may affect things it's going to go wrong and your picture is going to look fuzzy and the sharp edges will be affected.