I have experienced this first hand. I bought some general use switching supplies that I stuck in series to form a 28-0-28 supply. I added a whopping 40,000uf to the final series output and needless to say the supplies didn't like it. They started ticking and making other unusual sounds.
I'm not an expert in electronics so modding the feedback loop was out of the question. I managed to fix the problem in a newbish way by adding 0.1R in series before the caps and adding a constant 10w load across the supply.
Its been working good like this for about 9 months, but I would like to find a better solution. Maybe the SPS80 will make a good replacement. Is 40,000uf too much to add to the output of the SPS80 without any modifications to its feedback loop?
Here is a pic of my mess......
Nice pics! That must have cost you quite a bunch of dollars!
Adding 40000uF is quite a bit of capacitance. We think you won't need so much (have in mind that our SMPS is regulated so you really don't need as much capacitance as in a linear PSU in order to have a stable voltage) but anyway that should be tested.
If you want to order or have questions about our products, please don't use this forum and drop us an email.
best regards,
Sergio
Adding 40000uF is quite a bit of capacitance. We think you won't need so much (have in mind that our SMPS is regulated so you really don't need as much capacitance as in a linear PSU in order to have a stable voltage) but anyway that should be tested.
If you want to order or have questions about our products, please don't use this forum and drop us an email.
best regards,
Sergio
No, actually it was fairly inexpensive compared to other options, but then I got what I payed for too I guess.
All four supplies only cost me $70 total and the caps where $6 each.
I think I originally added so much capacitance because when I would play low frequencies through the amps the supplies would oscillate.
Pjotr said:Hi Sergio,
Interesting stuff those SMPSU. But IMHO SMPSU of this power level ask for PFC (Power Factor Correction). Are you planning this? Either incorporated in the PSU or as a separate input unit?
Regards
This sounds quite reasonable to ask, and in post 11 the same issue was addressed.
It could be interesting to see some emission/immunity results, or other signs of compliance with relevant mandatory requirements. Especially if using more than one PSU in the same enclosure.
RoHS/WEEE compliance information is also interesting, while we're at it.
Jennice
Jennice said:
Hi,
Don’t worry this is mandatory per end of this month, at least in the EC. But existing stock of existing equipment that is not compliant may still be sold until stocks are exhausted. New production must comply.
But apart from regulations, I would like to see a PFC in such a PSU especially for audio amplifiers.
The radiated noise from the power cord due to rectifiers and capacitor charging current pulses can be huge. Not only for SMPSU but also for a classic transformer PSU. It is just that with a SMPSU it can be elegantly solved by active PFC.
Just received this message from Jan-Peters!
"We have started with the design of a 1000W SMPS with PFC!!
This will be a complete Bruno Putzeys design, so we expect it will be very good¡K¡K J. We have some very smart plans, at the moment I can not disclose our design ideas¡K
The first planning was to keep these SMPS only for OEM¡¦rs, however there is so much interest from DIY people that we will make the SMPS available for everybody!
When everything goes ok, we will have the SMPS available at the end of this year."
"We have started with the design of a 1000W SMPS with PFC!!
This will be a complete Bruno Putzeys design, so we expect it will be very good¡K¡K J. We have some very smart plans, at the moment I can not disclose our design ideas¡K
The first planning was to keep these SMPS only for OEM¡¦rs, however there is so much interest from DIY people that we will make the SMPS available for everybody!
When everything goes ok, we will have the SMPS available at the end of this year."
Pjotr said:Hi Sergio,
Interesting stuff those SMPSU. But IMHO SMPSU of this power level ask for PFC (Power Factor Correction). Are you planning this? Either incorporated in the PSU or as a separate input unit?
Regards
To understand your message I went here:
http://en.wikipedia.org/wiki/Power_factor_correction
Active PFC seem the way to go.
Jan Peter is right: the PFC is a boost converter that typically outputs a constant voltage of around 400V independently of the input voltage. BUT in a wide range from 90 to 265VAC, the operating conditions of the PFC (duty cycle, etc) vary a lot and efficiency will be seriously affected in any of both ends.
If this is the main reason, I would choose a switch-selected input range and IMHO doesn´t justify the PFC added complexity and cost by itself.
If this is the main reason, I would choose a switch-selected input range and IMHO doesn´t justify the PFC added complexity and cost by itself.
Pierre said:
We have started with designing a 1000W SMPS + PFC. At this power level it is intersting to have a PFC.
Thereby we find it a big advantage if we do not have to use switches to change for different mains voltages. Besides this because of the PFC we will have a partly regulated SMPS.....
Jan-Peter
Hmm, do not agree with that Pierre.
With amps of higher power level the current spikes in the mains cord are huge and radiate a lot of noise in the range of 100 Hz to over 1 kHz. These can be picked up by signal cables. I have checked that with a spectrum analyser.
If you want to lower that with a classic PSU with a 50/60 Hz transformer you need a filter with huge chokes and capacitors and that is bulky and expensive.
A SMPSU requires a DC input and it is this that makes an active PFC possible. IMO the main advantage of PFC is that the charging of the input storage capacitor can be made sinusoidal with much lower charging pulses. That such a PFC makes it possible to have an universal input between 100V – 240V is more a commercial advantage.
Attached a pic what you get on de signal cables when they are 20 cm apart from a regular mains cord from an amp that is driven to about 100W.
Cheers
With amps of higher power level the current spikes in the mains cord are huge and radiate a lot of noise in the range of 100 Hz to over 1 kHz. These can be picked up by signal cables. I have checked that with a spectrum analyser.
If you want to lower that with a classic PSU with a 50/60 Hz transformer you need a filter with huge chokes and capacitors and that is bulky and expensive.
A SMPSU requires a DC input and it is this that makes an active PFC possible. IMO the main advantage of PFC is that the charging of the input storage capacitor can be made sinusoidal with much lower charging pulses. That such a PFC makes it possible to have an universal input between 100V – 240V is more a commercial advantage.
Attached a pic what you get on de signal cables when they are 20 cm apart from a regular mains cord from an amp that is driven to about 100W.
Cheers
Attachments
Jan-Peter said:
We have started with designing a 1000W SMPS + PFC. At this power level it is intersting to have a PFC.
Thereby we find it a big advantage if we do not have to use switches to change for different mains voltages. Besides this because of the PFC we will have a partly regulated SMPS.....
Jan-Peter
When do you plan it will become available to us?
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