Amiga Syncdoubler 




This circuit allows the Amiga users to kostenguenstige way 
A PalHiresScreen on a VGA monitor display. The Darzu 
Amiga line synchronous pulse phase doubled. 

Technical: 
The Amiga Hsync triggers IC1a and IC1b with the positive edge, is Ic1a 
4us set approximately equal to the VGA Sync, IC1b at 32us. After these 32us 
(Half Amiga line!) Will be triggered Ic1 again, and that was it! 


			Line X				Line X+1
		 ______________________________   _______________________
Amiga Hsync:   __|			      |__|
			Xa		Xb		X+1a		X+1b
		 _ _______________  _______________  ____________  _______
gen. VGAsync:    |_|		 |_|	          |_|		 |_|

	         ________________                ________________
Pin13 		 |               |_______________|               |_________

			None 		Image		None 		Image

Construction: 
The construction is happening fastest in a matrix board, dimensions: 
Approximately 2.5 x 5 cm if one takes spindle trimmer (recommended). 
A layout, which aetzen and to build on a matrix board - 
Is suitable, is attached. In the AmigaVGAAdapter now needs only the Hsync - 
Trace followed with a combined Syncdoubler (pin or 11 pin 
  10, compsync). The 5Volt for power supply are simply picked from the IC. 

Functional Test: 
If you are not so sure whether the built now that's what it will 
, The following can function test durchfuehren: the two C's will 
470uF with ueberbrueckt and at the output (pin 12) is a light-emitting diode 
. This muesste then burn (VCC = 5Volt not forget!). Per 
Hand is a positive change flank simulated. The Leuchdiode should now 
Twice in a row and acceptable. 
  

Balance: 
To balance reaches a multimeter. In the adjoining state and the 
Amiga Sync at the entrance, the voltage at the output of IC1a (Pin13) 2.5 
Volt (half VCC) is set, then the equivalent of a Tastverhaeltnis 
1:1. On the second Poti (2K of IC1b) is rotated until now to the VGA 
Monitor synchronized. Now must the left and the right half of the 
Amiga ueberlagert screens on the monitor to see. To the two sides 
And selected separately to see, you need the following addition: 

Three transistors (BC 547), about three Vorwiderstaende (1K) 
IC1a activated (pin or 13 pin 4), depending on the pin is the left or the 
Bildhaelfte right watch, a once switcher provides for the selection. 
The transistors close the RGB signal short (of mass emitter, collector 
An R, G and B). 

Compositions list: 
1x74Ls123 
2x10nF 
1xSpindeltrimmer 2K 
1xSpindeltrimmer 5K 
1x100nF 
3x1K 
3xBC547 
1XUmschlter 
1xLochrasterplatine 2.5 x 5cm 

Pin from the video port: 
Red 3 
4 Gruen 
5 blue 
10 compsync 
23 5V 
16-20 Mass 

This circuit has been successfully in an A4000 with a VisionMaster17 
And in a Yakumo tested. The Syncdoubler has the following features: 

- Extremely preisguentig 
Compatible with any software as hardware 
- Compatible with doublePal, MultiScan 
Standard Parts 
Just the left - 

This hardware is mail product, send me mail if your ne uses when 
There are suggestions, or just so. 


Bye, 
Dirk 


Fido 2:2432 / 360.6 BBS: 0515598138 
InterNet Dirk_Duesterberg@p6.f360.n2432.z2.ftg.donut.de