wats wrong with my ddl driver.

[TTerbo]

ok guys i made a ddl driver just to test a diode.
it uses a 200ohm pot and a 10 ohm resistor and i couldnt find any lm317 so i had to use a lm320?
when i apply a test oad and read the out put it starts at 120 then keeps geting lower.??
cheers

 

[lasersbee]

We need a schematic of EXACTLY what you put together...
with the exact part numbers you used....

remember......

The 1st thing YOU should do is a Google search for the LM320
Data Sheet...
Had you done that... you would have known that the LM320 is
a NEGATIVE Voltage regulator and not a Positive Voltage Regulator...

There are other reasons why the LM320 won't work in yout DDL
circuit but I'll let you find them on the LM320 Data Sheet..


Jerry

 

[TTerbo]

ok, i followed the usuall ddl driver schematic,
im pretty sure it was an lm320 it sais on it l7915cv
cc18b
marn443

now i will upload a pic if you need one

 

[lasersbee]

An LM320 and a 7915 are 2 different Regulators...
but both are Negative... and thec 7915 is a fixed
-15V regulator...


What is the number after the LM320-(X)...
Here is the Data Sheet...

http://www.datasheetcatalog.org/datasheets/270/49347_DS.pdf

Jerry

 

[TTerbo]

o dam. because wher i live you canot buy the lm317
any way i could make it work?
thanks lasersbee.
cheere

 

[lasersbee]

To make a Positive Current driver you will need an
Adjustable Positive Voltage Regulator...

Jerry

 

[TTerbo]

dont have any of those. darn my electronics shop is crap wont even let you order parts

 

[Cheech]

Jaycar Electronics in Australia
Jaycar Electronics - Search results lm317

 

[TTerbo]

yes i order from them but it takes a wile. my dad is going to necastle soon so i will get him to stock up on parts for me.
cheers

 

[Rafa]

Buy it online.
Or buy a comercial driver...