Bryan's Inverter build

Author	Message
mab1 Senior Member Joined: 10/02/2015 Location: United Kingdom Posts: 277	Posted: 10:43am 07 Mar 2026         tinyt said     Bryan1 said     tinyt said     Bryan1 said   3.44 volts measured on the left pin. That is too low, maybe your zener diode is not 18 volts. Measure the other two pins of the TIP31. And put back wires 1 and 2. OK took the ribbon out and tested the zener diode and 17.7 volts so the zener diode is correct mate. If your battery voltage is 24v-28v, that 120 ohms 5 watts resistor should be lower in value, maybe close to 60 ohms. Edit: But if your final battery voltage is 48-56 volts, then you have to restore it to 120 ohms. That's a very good point: at Vbat= 24v and R64=120ohms you're going to have less than 50mA drive current for all four totem pole drivers. 18 or 22ohms might be better for R64. R54 (r54 on the schematic, but looks like r64 on tinyt's pcb drawing) should be lower too: maybe 1k instead of 10K to provide enough base current for tip35. But i'm thinking it may be better if the powerboard was returned to the test bench, for better access for testing; once it's outputting 13v ac between vs1 and vs2 on the bench, it may be ready to go back in the cabinet with the big torroid. Edit again: Even if the above resistors are part if the problem, there has to be another issue causing the excessive current draw. Edited 2026-03-07 20:59 by mab1