Switched Mode Power Supplies (SMPS)

[Cristi]

To use the SMPS250 for a single rail supply, should add a resistor which will draw about 50-100mA from negative rail, this resistor must be rated at at least 3W in order to dissipate the power properly. a better solution is to reduce the output voltage to +-15V then to connect the load between V- and V+. this can be done if you connect in parallel with R30 a 47K resistor. please note that if the output voltage is too low, the smps can turn off due to low primary bias voltage and loosing of resonance.

[alkasar]

Originally Posted by Cristi

To use the SMPS250 for a single rail supply, should add a resistor which will draw about 50-100mA from negative rail, this resistor must be rated at at least 3W in order to dissipate the power properly. a better solution is to reduce the output voltage to +-15V then to connect the load between V- and V+. this can be done if you connect in parallel with R30 a 47K resistor. please note that if the output voltage is too low, the smps can turn off due to low primary bias voltage and loosing of resonance.

second method sounds nicer, but R30 is a cms resistor, to difficult for me to solder anything to this .
I'll go with the first method.
What about the power available on the positive rail : will it be the full 250W (400W peak) on only half of that ?

[col]

Hi Alkasar,

I think we are both attempting to do the same thing. I have now successfully tried both methods of connecting the SMPS in single ended mode. I think I will run with the second method as it seems more logical and balanced.

I am attempting to power one of the HiFiMediy V1.1B boards. I have done quite a few mods to my Connex SMPS250 including:

1. Cut 10mm off the top of the heatsink to fit into a 1RU rack case.
2. Changed the 400v 330uF cap for a 35mm high one.
3. Changed the 35v 6800uF caps for 30mm high 4700uF.
4. Changed the thermistor for a 10R 4.5A (15mm).
5. Added the 47k resistor in parallel to R30.

I think this is a much better alternative than the Meanwell 350W 24-27v "Brick" power supply as it is much smaller footprint and fits in a 1RU case (with my mods).

Cristi, perhaps you could manufacture a "Low Profile" version with the option for single ended supply controlled by a jumper? I think there are a lot of HiFiMediy customers that would be very interested.

col.

[alkasar]

Originally Posted by col

Hi Alkasar,

I think we are both attempting to do the same thing. I have now successfully tried both methods of connecting the SMPS in single ended mode. I think I will run with the second method as it seems more logical and balanced.

I am attempting to power one of the HiFiMediy V1.1B boards. I have done quite a few mods to my Connex SMPS250 including:

1. Cut 10mm off the top of the heatsink to fit into a 1RU rack case.
2. Changed the 400v 330uF cap for a 35mm high one.
3. Changed the 35v 6800uF caps for 30mm high 4700uF.
4. Changed the thermistor for a 10R 4.5A (15mm).
5. Added the 47k resistor in parallel to R30.

I think this is a much better alternative than the Meanwell 350W 24-27v "Brick" power supply as it is much smaller footprint and fits in a 1RU case (with my mods).

Cristi, perhaps you could manufacture a "Low Profile" version with the option for single ended supply controlled by a jumper? I think there are a lot of HiFiMediy customers that would be very interested.

col.

Yes, we attempt to do the same
I agree that second method looks "cleaner" but I am scared to solder a resistor in parallel to a cms.
Could you post a close-up image showing how it looks like once done ?

For Cristi : +1 for a low profile and single voltage option. The next demand will be for a 48-50V smps for the high power T3 amp. Many people pick the large "meanwell brick" because no other easy option available.

[Cristi]

I suggest to not reduce the output voltage below 60% of the actual limit, because the Power Switch can lose the bias voltage and also the smps will run in hard-switching instead of QR mode.

I'm working at a new smps version with single output voltage as well.

[kingnubian]

Originally Posted by Cristi

the aux. voltage is 2x20V DC, at max. 0.5A. the main voltage is adjustable within max. +-10%, that's because the topology used requires tight output voltage to maintain the operation within ZVS range. the output voltage can have one of the following values: +-30V, +-40V, +-50V, +-60V, +-70V all +-5-10% adjustable

I wish to have the SMPS500R Power my ClassDAudio SDS-254 amp with it's primary (50V I believe) & use the 20v Aux to power a Pass B1 preamp (Making a performance integrated amp) in the same chassis.

Is this possible??

[SoldierAnt76]

Any idea when the single voltage SMPS might be available? If it's no higher than 1U (about 44mm), and no wider than about 75mm or 3", then it'll be perfect for installation in a case.

Most electronics project boxes are only 50mm high at most, and usually no wider than 150mm or so. So it's hard to find a power supply that can fit inside an enclosure with an amplifier board.

[robob]

Hi,
I apologize for my english.

I got the Sure-electronics tripath 4 X100w tk2050 board that you certainly know. I'm using a Meanwell power supply (recommended and sold by Sure ) for this board (350W, 24V , 16.4 A). But this PS is too big (22 x12 x 5 cm) and i'm looking for a smallest one. Have you any SMPS wich can match my T-amp ?

[alexberg]

Originally Posted by robob

Hi,
I apologize for my english.

I got the Sure-electronics tripath 4 X100w tk2050 board that you certainly know. I'm using a Meanwell power supply (recommended and sold by Sure ) for this board (350W, 24V , 16.4 A). But this PS is too big (22 x12 x 5 cm) and i'm looking for a smallest one. Have you any SMPS wich can match my T-amp ?

It's very reasonable size. Assuming efficiency 85% it dissipates around 50W, so comes built-in fan.
You may try Vicor's bricks with high pressure fan and channel fin heatsink - are you ready for the noise... or liquid cooling?

[robob]

Sorry, I don't understand your answer :

MY question is, can I use the SMPS250QR or may be the connexelectronic A350SMPS or any other one power supplies with my 4 x 100W tk2050 t-amp ? I suppose I need around 350 W, 24 V and 16.4 A : for example I don't found any amperage indication for the SMPS250QR and I don't know if it's important (I suppose it is ).