Electrohome ECP 4100 Series User Manual download pdf

VGA to RGB + composite sync -converter

This article consists of one circuits which I have designed for connecting VGA card to other display devices than

just a VGA monitor. This circuits makes it possible to connect your VGA card to fixed frequency monitors and video

projectors. For some applications and system combinations some additional software is needed to get the system

working.

I keep all the rights to this circuit. You can freely build this circuit for your own use but you are not allowed to use

those circuit designs commercially without written permission from the designer.

VGA to RGB + Composite Sync converter

First circuit is for connecting VGA card to video projector or a monitor which accept VGA card frequencies and has

RGB + Composite sync input. This circuit has been succesfully used with Electrohome Projection Systems ECP

4100 data and video projector.

This circuit is designed for converting normal VGA signals standard RGB signals and composite sync signal. The

circuit is quite simple, because RGB signal ouput from VGA card is already standard 0.7Vpp to 75 ohm load.

For sync signals there is a circuit which combines horizonal and vertical sync signals to form composite sync

singals. The circuit is simply based on one TTL chip with four XOR ports, two resistors and two capacitors. TTL

chip ws logical choise because VGA sync signals are TTL level signals.

The sync signal combiner has a system to adjust to different sync polarities so that it always makes correct

composite sync signals. VGA card uses different sync signal polarities to tell the monitor which resolution is used.

This circuit adjusts to sync signal polarity changes in less than 200 milliseconds, which is faster than setting time of

a normal VGA monitor in the display mode change.

Analogue composite sync signal converter

First circuit is for connecting VGA card to video projector or a monitor which accept VGA card frequencies and has

RGB + Composite sync input (1 Vpp signal level, 75 ohm input impedance).

This picture is available in

GIF and Postscript versions.

Note: The circuit diagram does not show the wire giving power to IC1. The +5V power is connected to pin 14 and

ground is connected to pin 7.

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Summary of Contents

Page 1

VGA to RGB + composite sync -converter Designed by Tomi Engdahl This article consists of one circuits which I have designed for connecting VGA card t

Page 2

This circuit has been succesfully used with Electrohome Projection Systems ECP 4100 video projector in many VGA and SuperVGA modes. The circuit have b

Page 3

Component list C1 22 uF 10V electrolytic C2 22 uF 10V electrolytic R1 2.2 kohm R2 2.2 kohm U1 74LS86 or 74HCT86 Simple sync c

Page 4

Component list C1 22 uF 10V electrolytic C2 22 uF 10V electrolytic R1 2.2 kohm R2 2.2 kohm U1 74LS86 or 74HCT86 Connecting V

Page 5

Output connector: 75 ohm BNC connectors (you need 4 BNC connectors) Wiring: Red, Green, Blue and Composite Sync lines should be wired using 75 ohm co

Page 6

How to use old video projectors and TV studio monitors If you happen to own an old video projector which is capable of displaying only PAL/NTSC/SECAM

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Electrohome ECP 4100 Series User Manual

Browse online or download User Manual for Projectors Electrohome ECP 4100 Series. VGA to RGB + composite sync

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