praganj;586100 Wrote: > Hi John, > > I have few questions: > > 1. What AC voltage should deliver the transformator and how big ;) > should it be ? > 2. R1 - 1W is enough ? > 3. Can i use instead of LT1048 one superteddyreg and if yes, is C5 and > C6 necessary ? Or should i just forget str and use LT1048 ? > 4. When i am building it and measuring, what voltage exactly should be > after choke and after reg ? > > Thanks, p.
1, this design uses 10VAC out of the transformer. A little larger won't hurt, it just means the the regulator has to dissipate more power. How big dpends on whether you will be running a USB disk drive off it. If not using a bus powered drive 25VA and up is fine. If you want to run a drive off this I would go for 50VA. 2. I'm using a 1/2W carbon composition resistor. 3. Sure you can use other regulators if you want, just make sure you have enough voltage for the regulator drop out. This design was tuned for the dropout of the LT1084, (I don't remember off the top of my head, you can look it up). If the regulator you want to use has a a greater drop out voltage you will have to up the voltage on the transformer. This design is very easy on transformers so you do not need to significantly over rate them. 4. You want the output to be 5V, it doesn't have to be super exact. 5.1 V will be fine, don't go much below. 4.98 is fine, but 4.8 might be too low. Don't go above 5.2 V. As to the output of the choke, that depends on the dropout of the regulator in use. If you are going for 5V out and your regulator needs 2V dropout, the output of the choke should NEVER go below 7V. Give your self a little margin. John S. -- JohnSwenson ------------------------------------------------------------------------ JohnSwenson's Profile: http://forums.slimdevices.com/member.php?userid=5974 View this thread: http://forums.slimdevices.com/showthread.php?t=82648 _______________________________________________ Touch mailing list [email protected] http://lists.slimdevices.com/mailman/listinfo/touch
