futurewave
New Member
I used one of the suggested circuit in LM317 data sheet from national semi (page 8), in order to build up a (2-30V 3A) power supply. Due to lack of some components in my location I changed the current amplifier transistor MJ4502 to MJ2955 and also LM301 op amp to (NE5532 or TL071).
The transformer is rated for 24V AC 3A and I got a wide voltage range (1.25-32V DC) with this circuit. the problem is, while the load current increases the output voltage will increase a little too for example at 13 V DC with different loads the result is something like this:
100 ohm load --> 13.03 v
33 ohm load --> 14.15 !
15 ohm load --> 15.32 !!
I think the output voltage must be constant, and there must be something wrong with this regulation.
Any Idea about this ?
The transformer is rated for 24V AC 3A and I got a wide voltage range (1.25-32V DC) with this circuit. the problem is, while the load current increases the output voltage will increase a little too for example at 13 V DC with different loads the result is something like this:
100 ohm load --> 13.03 v
33 ohm load --> 14.15 !
15 ohm load --> 15.32 !!
I think the output voltage must be constant, and there must be something wrong with this regulation.
Any Idea about this ?