schmidtbag
- Nov 8, 2012
- 36
- Joined
- Nov 8, 2012
- Messages
- 36
The IC says UC8848A, 1119QX
Last edited:
If you look at the picture of the back side, you can see the in+, in-, out+, and out-. I put the resistor at the out+, and put the + multimeter terminal to that while putting the - terminal to in-.You put a 56K resistor "at the output terminal"? I don't know what you mean.
Then why didn't you? I didn't need to specify what the timpot value was in order to figure that out. Nobody this entire time (including right now) has explained why I was getting the results I was getting. When I think of increasing the resistance, I think of voltages dropping, not getting higher. Anyways, considering that the trimpot/resistor basically can't single handedly drop the voltage to 24v, I also don't understand what that controller on the bottom can do about it. I'm not saying that it isn't related, but I just don't see how a tiny un-cooled IC could have a direct relation to what I'm trying to accomplish.I could have told you that reducing the trimpot resistance would reduce the output voltage. That is why you can't get 24V by changing the resistance in the trimpot position. You can't reduce that resistance below zero.
What mistake? Putting the resistor at the output? And I'm not deciding to ignore advice, I'm trying out my options to see what works while I wait until the sun comes up, and so far I got desired results on my own (although, I'm not sure how safe it is to have about 120W running through a tiny resistor, but nobody has yet explained if it is or isn't).I'm still happy to try to help, when you discover the mistake you have made and are prepared to listen to advice again.
WHAT...IS...THE...RESISTANCE...MARKING...ON...THE...TRIMPOT?
............. I also don't understand what that controller on the bottom can do about it. I'm not saying that it isn't related, but I just don't see how a tiny un-cooled IC could have a direct relation to what I'm trying to accomplish.
Thanks, I'd already recognised that from the pin connections. He said it's a UC8848A, which I can't find anywhere. There IS a 3848, but it has 16 pins. Maybe the 8848 is a third-party 8-pin version of the 3848 with the same pinout as the 3842/3/4/5.Kris, the controller might be this (UC3843A) or something substantially similar.
Yes, I saw that. Somehow I got the idea that his board was different from the advertised board in some way. So I wanted to check that the trimpot was the same value.Ebay auction photo shows it as a 10K (103)...
I THINK you're saying that you put the resistor between the +OUT connection and the multimeter's positive probe. That may make the multimeter SHOW 24V, but it won't make the power supply output equal to 24V. If you connect your load after the resistor, there will be almost no current available, and the voltage will drop to (near) zero, as duke said in the previous post.If you look at the picture of the back side, you can see the in+, in-, out+, and out-. I put the resistor at the out+, and put the + multimeter terminal to that while putting the - terminal to in-.
Your understanding of this circuit, and basic electronic theory, is a drop in the ocean, I'm afraid. I didn't tell you that decreasing the trimpot resistance would decrease the voltage because I didn't know that you had assumed the opposite. Your explanations are not very clear.Then why didn't you? I didn't need to specify what the timpot value was in order to figure that out. Nobody this entire time (including right now) has explained why I was getting the results I was getting. When I think of increasing the resistance, I think of voltages dropping, not getting higher. Anyways, considering that the trimpot/resistor basically can't single handedly drop the voltage to 24v, I also don't understand what that controller on the bottom can do about it. I'm not saying that it isn't related, but I just don't see how a tiny un-cooled IC could have a direct relation to what I'm trying to accomplish.
Yes, that mistake. I suggest you get some sleep. Maybe you will be able to concentrate better when you wake up.What mistake? Putting the resistor at the output? And I'm not deciding to ignore advice, I'm trying out my options to see what works while I wait until the sun comes up, and so far I got desired results on my own (although, I'm not sure how safe it is to have about 120W running through a tiny resistor, but nobody has yet explained if it is or isn't).