Electronics > Beginners
lab power supply
MarkF:
Since you only want an adjustable supply with less than 1A, I suggest you go back to basics and get that working first.
If the digital volt meter you want to use covers the maximum output voltage the LM317 will be set to, you can just wire it directly to the outputs.
--- Quote from: glinjik on December 17, 2019, 04:57:03 pm ---i installed a 450v 150mf cap and that seems ok my little melt down did destroy both 2n3055's what im thinking now is no load i get a steady22.02v under load it drops to 19.59v its only a 12v led light as a load what im wondering is this can it be made more stabe?
--- End quote ---
If the 150uF 450V cap is all you have on the input, it's way too small.
You will have a large ripple on the input to the LM317 with it.
You need something in the range of 6800uF @ 50V to not have that voltage drop on the output.
What is the rating of the transformer secondary you are using?
Put the fan control you shown across the 'input' of the LM317.
glinjik:
--- Quote from: MarkF on December 17, 2019, 07:11:27 pm ---Since you only want an adjustable supply with less than 1A, I suggest you go back to basics and get that working first.
i have it working :) ijust want to inprove it the fan control does work its on a seperate board at the moment if i have space i will put it on main board also want to add short circuit protection with transistors not relay its coming together nicely th cap will have to wait untill my next trip to town maybe a few weeks unless i scrounge one someplace the transformer is i cant get any data on although it came from a drill battery charger i think i got about 3 amps out of it befor the caps blew up
--- End quote ---
rdl:
What is the output voltage of the transformer secondary?
glinjik:
output voltage is 19.81vac and 26vdc after rectification and output from circuit 22.38vdc interesting i can get as low 3.4mv unloaded mv under load is mainly impossible to control need to put in a secondery volt control
glinjik:
update to my beginner’s power supply all working as it should no problems yet although lm317 does not seem to be getting warm i added a small heatsink anyway as with the bridge rec just in case also added connectors for volt control. the 2n3055's and volt meter next want to change the current control to a potentiometer and also put that on a connector the output will also change to a clip connector I figured if I blow it up it will be east to remove the board from the case just using clips, next is fan control once that’s working I will add it to the schematic for any other beginners I’ve part done the schematic for any one’s interest
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version