powering ps1 screen

new york cheech · Post by **new york cheech** » Fri Jul 22, 2005 10:23 pm

could someone tell me if this would work

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... =WD1V&rd=1

*o* · Post by ***o*** » Fri Jul 22, 2005 10:29 pm

nos_slived · Post by **nos_slived** » Sat Jul 23, 2005 12:04 am

That's a good deal. You can use 7805s as adjustable regulators to achieve 8V.

BTW, the PS1 screen can take anything between 7.2V and 9V.

PS, what's your power source?

*o* · Post by ***o*** » Sat Jul 23, 2005 1:17 am

tell me more bout that 7805 thing??

nos_slived · Post by **nos_slived** » Sat Jul 23, 2005 1:52 am

Vout = Desired output voltage
Vfixed = Fixed voltage of IC regulator (5 volts for 7805 or 1.25 volts for LM317T)
R1 = Assume any value from about 470 to 1K for best results
Istndby = Standby current of regulator (use 2.5mA for 7805 or zero for LM317T)

Use the formula: Vout = Vfixed + R2[Vfixed/(R1 + Istndby)]. R1 is usually 470 ohms, but can go as high as 1K ohm.

For example, to get 8V, you can use:

Code: Select all

Vout = Vfixed + R2[Vfixed/(R1 + Istndby)]
8 = 5 + X[5/(470+2.5)]
8 - 5 = X[5/(472.5)]
3 = X[0.01050105821....]
3/0.0105.... = X
X = 283.5
R2 = 283.5 ohm

This is an approximate calculation, and you should test the voltage of this with a multimeter before using this.

NOTE: When resistors get hot, their resistance goes up so your output will change slightly. I recommend running this for a while to test it's output while the resistors are warm.