That’s a great little chassis test bed. I have one I’ve put a couple different amp modules in. Currently have @abraxalito class D amp boards in it. Do you plan to have a circuit for the meters? Looking forward to your developments.
DC offset up to 100mV is not a problem but if you want to make it lower, the easiest way to do it is to put a serial connection of 120R resistor+ 50R multiturn pot instead of R8 or R5 so you can adjust it.
Of course, there are other methods: transistors' thermal coupling and/or transistors' matching as well as adding a DC servo circuit etc... There are a lot of posts/threads on these subjects, be free to search the forum/net.
Last edited:
Since there are several solutions, it would be easier to offer the easiest solution if you would include more information of your layout, especially a photo. You will notice from post #1 that juma included a pot in series with a slightly smaller value of R8. If adding in a pot makes it too messy on your layout, then you could find it easy to parallel a resistor with R5 to bring the R8 to R5 leg slightly more negative. That is if the present offset is +71mV and not -71mV. Maybe try a resistor value between 2k2 and 3k3. Small steps are better than big jumps. After you see the amount of change you can use the formula for parallel resistance to calculate a better value resistor.
Would you also measure and post the amount of heat rise you have along with a photo of your heat sink? That may help others judge how much heat sink they need for this circuit. It looks like a very nice circuit that needs only low-cost, easy to obtain parts.
Would you also measure and post the amount of heat rise you have along with a photo of your heat sink? That may help others judge how much heat sink they need for this circuit. It looks like a very nice circuit that needs only low-cost, easy to obtain parts.
Thanks sirDC offset up to 100mV is not a problem but if you want to make it lower, the easiest way to do it is to put a serial connection of 120R resistor+ 50R multiturn pot instead of R8 or R5 so you can adjust it.
Of course, there are other methods: transistors' thermal coupling and/or transistors' matching as well as adding a DC servo circuit etc... There are a lot of posts/threads on these subjects, be free to search the forum/net.
Currently, I don’t have anything to measure the temperature. After 3 hours of working, temperature of lateral mosfet is normal only.
I think below mentioned heatsink size is appropriate
Length-25cm Width-4cm Height-11.5cm
Please find the attached snap for reference
Attachments
Sir, can i use 100ohm multiturn port?DC offset up to 100mV is not a problem but if you want to make it lower, the easiest way to do it is to put a serial connection of 120R resistor+ 50R multiturn pot instead of R8 or R5 so you can adjust it.
Of course, there are other methods: transistors' thermal coupling and/or transistors' matching as well as adding a DC servo circuit etc... There are a lot of posts/threads on these subjects, be free to search the forum/net.