This is the startup current waveform for 12V input and a 140 mA load indirectly measured across a 0.22R resistor.
DC Input - Bipolar Output Switcher PC Boards for Small Projects
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mediatechnology
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Re: DC Input - Bipolar Output Switcher PC Boards for Small Projects
I'm fairly confident the bigger "bricks" will run it.
This is the startup current waveform for 12V input and a 140 mA load indirectly measured across a 0.22R resistor.
This is the startup current waveform for 12V input and a 140 mA load indirectly measured across a 0.22R resistor.
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mediatechnology
- Posts: 5818
- Joined: Sat Aug 11, 2007 2:34 pm
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Re: DC Input - Bipolar Output Switcher PC Boards for Small Projects
I received the Meanwell switcher and Triad linear DC wall-mount transformer to test with the DROK and Flat Moving Coil Preamp.
Both handle the start-up current.
The Meanwell is PN NGE45U12-P1J for the US 2-blade plug version. It is rated 12V at 3.75A 45W. The Mouser number is 709-NGE45U12-P1J.
It's a nice supply with folding blades.
The Triad is PN WDU12-600 12V 600 mA and is available only in the US. The Mouser number is: 553-WDU12-600.
The FFT noise floors, when nulled to reduce ambient room hum, are virtually identical to each other and the linear bench supply over a 48 kHz BW.
When the Triad is used its flux leakage contributes to the ambient magnetic field but it has a 6 foot cord and physical separation reduces it to the background hum level of the room.
Since the FMCP board pulls more than the minimum load current I'm going to remove the pre-load resistors which dissipate 1W each and check start-up since it looks like the lesser the load, the greater the peak current which is counter-intuitive.
A also looked at the DROK bipolar output voltages at start-up and they ramp up linearly with an insignificant amount of overshot and rapid settling. Overall it's quite controlled unlike the input side current.
Both handle the start-up current.
The Meanwell is PN NGE45U12-P1J for the US 2-blade plug version. It is rated 12V at 3.75A 45W. The Mouser number is 709-NGE45U12-P1J.
It's a nice supply with folding blades.
The Triad is PN WDU12-600 12V 600 mA and is available only in the US. The Mouser number is: 553-WDU12-600.
The FFT noise floors, when nulled to reduce ambient room hum, are virtually identical to each other and the linear bench supply over a 48 kHz BW.
When the Triad is used its flux leakage contributes to the ambient magnetic field but it has a 6 foot cord and physical separation reduces it to the background hum level of the room.
Since the FMCP board pulls more than the minimum load current I'm going to remove the pre-load resistors which dissipate 1W each and check start-up since it looks like the lesser the load, the greater the peak current which is counter-intuitive.
A also looked at the DROK bipolar output voltages at start-up and they ramp up linearly with an insignificant amount of overshot and rapid settling. Overall it's quite controlled unlike the input side current.
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mediatechnology
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- Joined: Sat Aug 11, 2007 2:34 pm
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Re: DC Input - Bipolar Output Switcher PC Boards for Small Projects
Preloading the output of the DROK switcher is a requirement even if the load exceeds the pre-load current.
I read the reviews on this product and some users noted that if the input supply is ramped up slowly that around 4V the supply will run open loop and produce about 70V between the + and - outputs.
I confirmed that mine produced 75V and it will provide high current when doing so.
When pre-loaded in 470Ω per leg, 32mA, the output will peak at 31.75V or about 16V/output.
This is an acceptable number.
Here is an example assembly I used to run the Flat Moving Coil Preamp.
I also ran the Dual Class-A Headphone Amp from it which pulls around 240 mA.
The 470Ω 1W pre-load resistors (Vishay PR01) are standing on end and connect to the 0.1" header connector.
The input and output leads are soldered to the pads on 0.2" centers.
As can be seen from the 1" grid paper the board is 2.6" x 1.1".
DROK Bipolar Switcher Assembly
I read the reviews on this product and some users noted that if the input supply is ramped up slowly that around 4V the supply will run open loop and produce about 70V between the + and - outputs.
I confirmed that mine produced 75V and it will provide high current when doing so.
When pre-loaded in 470Ω per leg, 32mA, the output will peak at 31.75V or about 16V/output.
This is an acceptable number.
Here is an example assembly I used to run the Flat Moving Coil Preamp.
I also ran the Dual Class-A Headphone Amp from it which pulls around 240 mA.
The 470Ω 1W pre-load resistors (Vishay PR01) are standing on end and connect to the 0.1" header connector.
The input and output leads are soldered to the pads on 0.2" centers.
As can be seen from the 1" grid paper the board is 2.6" x 1.1".
DROK Bipolar Switcher Assembly