hello everyone
Recently, I need to make a micro power consumption high voltage low current (<1mA) boost power supply.
Is there any simple circuit for boosting 30V to 60-70V
Recently, I need to make a micro power consumption high voltage low current (<1mA) boost power supply.
Is there any simple circuit for boosting 30V to 60-70V
I went over to the ADI site and turned up this chip - https://www.analog.com/en/products/lt8494.html#product-overview
Thank you friend!
It's too expensive for me
I want to find a simpler boost mode or cheap chip that can boost 30VDC to 60V or 70V, with very low requirements for current
Something like this is cheap but probably won't have very low current requirements - https://www.aliexpress.us/item/3256804327536961.html
This is a DC-DC modular power supply,
It's too big for me. I can't use such exaggerated modules
I want to get it through a simple voltage doubling oscillation circuit, but I can't find the relevant drawings
I suggest you list all your requirements at the start then DIYers won't be making suggestions which get rejected because there were some hidden specs that you didn't share.
This type of converter followed by a voltage doubler would be suitable, and could use an ordinary 68µH choke, since the output doesn't need to be isolated:
https://www.diyaudio.com/community/...ed-as-low-tech-converters.297568/post-4848112
It is simple, cheap and reliable.
If you are interested, I can modify the sim for a supply of 30V, and I can even check it on a breadboard: it is a 5 minutes affair
https://www.diyaudio.com/community/...ed-as-low-tech-converters.297568/post-4848112
It is simple, cheap and reliable.
If you are interested, I can modify the sim for a supply of 30V, and I can even check it on a breadboard: it is a 5 minutes affair
Here is a possibility: it delivers 66V DC @ 1.1mA, and it is regulated by D3 and D4 (you can use other voltages. They see 0.35mA, which is the regulation margin.
The input voltage is (voluntarily) on the low side, and the input current is <5mA.
I am going to make a reality check
The input voltage is (voluntarily) on the low side, and the input current is <5mA.
I am going to make a reality check
I have tested the circuit:
No surprise, it works as expected.
Some remarks: for the test I have connected C3 to GND instead of V+. This is electrically equivalent, but if the circuit is switched on instantly, it prevents the gate of the MOS from seeing the full supply voltage.
In the original application with a capacitive supply, the voltage was rising slowly and presented no risk.
The connection to V+ is in principle preferable, because the AC currents do not need to pass through the supply impedance, but with a good bypass, this is not an issue.
On the pic, you can see the yellow 0.22µF acting as bypass.
I have tested a slightly modified version, including a free-wheeling diode to prevent the clamping of the signal by the body diode of the MOS:
As you can see, there is no bottoming of the waveform, allowing a higher output voltage if required.
This is the circuit without D5, where bottoming is clearly visible:
And this is the actual waveform (with D5):
Regarding the components, C1 has to be of a "tuning" grade: PP, PS, and also group I ceramics: COG is the best-known, but other grades are suitable, N750 or even N1500.
C2 is less important, but it should be a mylar type, not a high k ceramic. X-type could probably still work but not Y or Z.
C3 is unimportant.
D5, if used should preferably be a schottky. C4 can be increased at will.
The choke is a standard microchoke.
No surprise, it works as expected.
Some remarks: for the test I have connected C3 to GND instead of V+. This is electrically equivalent, but if the circuit is switched on instantly, it prevents the gate of the MOS from seeing the full supply voltage.
In the original application with a capacitive supply, the voltage was rising slowly and presented no risk.
The connection to V+ is in principle preferable, because the AC currents do not need to pass through the supply impedance, but with a good bypass, this is not an issue.
On the pic, you can see the yellow 0.22µF acting as bypass.
I have tested a slightly modified version, including a free-wheeling diode to prevent the clamping of the signal by the body diode of the MOS:
As you can see, there is no bottoming of the waveform, allowing a higher output voltage if required.
This is the circuit without D5, where bottoming is clearly visible:
And this is the actual waveform (with D5):
Regarding the components, C1 has to be of a "tuning" grade: PP, PS, and also group I ceramics: COG is the best-known, but other grades are suitable, N750 or even N1500.
C2 is less important, but it should be a mylar type, not a high k ceramic. X-type could probably still work but not Y or Z.
C3 is unimportant.
D5, if used should preferably be a schottky. C4 can be increased at will.
The choke is a standard microchoke.
An additional remark: D2 and C5 look dispensable. Without them, the circuit should work in exactly the same way (though not if the free-wheeling diode is present), but in practice, if the load is essentially resistive, the current from V+ drawn by D1 will make it conduct, act as a PIN diode and paralyse the oscillator because the tank circuit will be shunted by the filter cap C4.
Thus, the oscillator won't be able to start by itself.
If the load is electronic and sufficiently non-linear, the oscillator might be able to start by itself, but this needs to be tested. With C5, it will always start, even on a dead short
Thus, the oscillator won't be able to start by itself.
If the load is electronic and sufficiently non-linear, the oscillator might be able to start by itself, but this needs to be tested. With C5, it will always start, even on a dead short
if it is for condenser bias, here is a nice circuit that I posted some time ago: https://www.diyaudio.com/community/...ifier-i-made-has-no-sound.388490/post-7081112
Dear friend
Thank you for providing the circuit. I would like to ask about the current consumption of the circuit itself,
The current provided for 48V phantom power supply is only 10mA, which does not include the impedance transformation part of the capsule. Will the 48V voltage drop to 30V or lower?
Thank you very much for everything you have done for me.
I have placed an order for relevant electronic components on the website. Using the circuit you provided, I intend to use chip resistors and capacitors to make control PCB sizes
the tail current of the pair is regulated by pulling R1 1.2K resistor low. the bases are biased at the 1.2V reference level, so the emitters are at 0.6V. so the oscillator cannot draw more than 0.5mA. The audiostage ( not depicted) used 2 pnp followers (emitter resistors are the 6.8k phantom power resistors in the desk) that have the collector connected to a 24V zener diode.