Hello friends.
I need to make 9v to 48v dc dc conversion (for powering a condenser mic from 9V battery) . I found this schematic 9V to 48V DC-DC Converter
The problem with this schematic is that when I adjust about 40V output - it consumes about 60mA. It's too much. Lowering the output voltage lowers the consuming current. All the above was tested without any load (with mic as a load the picture is almost the same). According to the schematic L1 should be 68uH. When I used this value I burned the chip. Then I replaced it with 470uH (exactly this value is used in the real board on the photo). I also replaced 0.33 ohm resistor with a jumper.
I measured the consumed current as voltage drop on 33 ohm resistor connected between the plus of the battery and the plus of the pcb.
The question is how can I increase the efficiency of the schematic or maybe someone knows other schematic with low consumption.
Thanks!
I need to make 9v to 48v dc dc conversion (for powering a condenser mic from 9V battery) . I found this schematic 9V to 48V DC-DC Converter
The problem with this schematic is that when I adjust about 40V output - it consumes about 60mA. It's too much. Lowering the output voltage lowers the consuming current. All the above was tested without any load (with mic as a load the picture is almost the same). According to the schematic L1 should be 68uH. When I used this value I burned the chip. Then I replaced it with 470uH (exactly this value is used in the real board on the photo). I also replaced 0.33 ohm resistor with a jumper.
I measured the consumed current as voltage drop on 33 ohm resistor connected between the plus of the battery and the plus of the pcb.
The question is how can I increase the efficiency of the schematic or maybe someone knows other schematic with low consumption.
Thanks!
Last edited:
The 0.33 resistor is importent, it keeps the peak current under 1A.
C5 must be low ESR.According to the factory data, the zero load current is max.4mA.There is allready a load by the voltage divider R3+R4.Total consuption goes up over 10mA no load.To lower consumtion, try a bigger C1 to lower operation frequency.Factory data use 1n ... 1n5.
Mona
C5 must be low ESR.According to the factory data, the zero load current is max.4mA.There is allready a load by the voltage divider R3+R4.Total consuption goes up over 10mA no load.To lower consumtion, try a bigger C1 to lower operation frequency.Factory data use 1n ... 1n5.
Mona
The converter of this tester has a much more reasonable consumption (depends mainly on the quality of the inductor).
It is the upper part of the circuit, around the 4069
As it is, it's a constant-current, voltage-limited type of 20V or 200V, but it can easily be converted.
For 48V, you would need to make R7 ~1.3 Megohm.
You could keep the current limitation, it will protect against shorts, and phantom power normally needs next to nothing, but if you want to remove it, use a simple transistor instead of the optocoupler, and remove R5, R6.
The voltage regulation isn't tight, which shouldn't be a problem in your case, but if you want to tighten it, you could use a 39V zener in series with 220K in place of R7.
It is the upper part of the circuit, around the 4069
As it is, it's a constant-current, voltage-limited type of 20V or 200V, but it can easily be converted.
For 48V, you would need to make R7 ~1.3 Megohm.
You could keep the current limitation, it will protect against shorts, and phantom power normally needs next to nothing, but if you want to remove it, use a simple transistor instead of the optocoupler, and remove R5, R6.
The voltage regulation isn't tight, which shouldn't be a problem in your case, but if you want to tighten it, you could use a 39V zener in series with 220K in place of R7.
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