Electronics > Beginners
Need tips on building a variable power supply
jah118:
--- Quote from: wasyoungonce on November 24, 2018, 04:34:35 am ---Jah...do you have a link to the original PSU page?
Thanks
--- End quote ---
no sorry, i have the design from an old homework assignment, i found in my dads old things.
jah118:
--- Quote from: mvs on November 24, 2018, 03:23:02 pm ---
--- Quote from: not1xor1 on November 24, 2018, 12:44:25 pm ---BTW would a new thread in the project section would be more appropriate?
--- End quote ---
If you plan to implement and verify your design in hardware... maybe yes. Otherweise it makes not much sense.
There is almost nothing special in your design... emitter folower and 2 error amplifiers. LT1013 is also strange choise, since it is quite slow and has odd pinout for dual opamp.
The only thing i liked, is usage of Sziklai pair instead of Darlington.
just my 2 cents
--- End quote ---
The reason for needing a power supply that can deliver 30V min 5A is, i need for some battery charging, and when summer comes around i need make an Peristaltic Pump with an motor that needs 24v and 4-5A to drive and would be nice to have power supply to test it on.
wasyoungonce:
Thanks to your dad jah118 ....I just recently saw similar on the net.
5 amps for a pertalilistic pump is a lot. Ours (pool acid pump) was a 24v geared used around 600mA. But acid pumping is a whole world of hurt (corrosion)
Sent from my iPhone using Tapatalk
not1xor1:
--- Quote from: jah118 on November 28, 2018, 08:33:02 pm ---
--- Quote from: David Hess on November 23, 2018, 07:03:01 pm ---10 amps at 30 volts is beyond what a single power transistor can handle reliability without fold-back current limiting; 20 volts at 1.5 amps would be more realistic so I suggest building a lower power supply to gain more experience first.
The design as shown is certainly workable although the current limit is pretty basic.
--- End quote ---
hmm. i think i then will have to run 3 or 4 of them(2n3055) in Parallel,(and i have som massiv coolers from and old radio)
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3 devices would just be barely within the specified SOA. 4 transistors or even more would be much better considering that the datasheet SOA is relative to an ideal 0K/W heatsink.
In case of short the PSU would dissipate more than 350-400W (you have to take into account that the unregulated voltage must be higher than the maximum output one).
In another message you wrote that you would use it as battery charger or for a pump.
For such kind of load it would be better to use a switching PSU followed by one of those programmable switching regulators sold on ebay/alibaba/bangood...
I think the manufacturer is ruideng
here it is:
https://www.banggood.com/DPS3012-32V-12A-Buck-Adjustable-DC-Constant-Voltage-Power-Supply-Module-Integrated-Voltmeter-Ammeter-p-1065235.html?rmmds=search&cur_warehouse=CN
dzseki:
--- Quote from: not1xor1 on November 29, 2018, 10:34:05 am ---
--- Quote from: jah118 on November 28, 2018, 08:33:02 pm ---
--- Quote from: David Hess on November 23, 2018, 07:03:01 pm ---10 amps at 30 volts is beyond what a single power transistor can handle reliability without fold-back current limiting; 20 volts at 1.5 amps would be more realistic so I suggest building a lower power supply to gain more experience first.
The design as shown is certainly workable although the current limit is pretty basic.
--- End quote ---
hmm. i think i then will have to run 3 or 4 of them(2n3055) in Parallel,(and i have som massiv coolers from and old radio)
--- End quote ---
3 devices would just be barely within the specified SOA. 4 transistors or even more would be much better considering that the datasheet SOA is relative to an ideal 0K/W heatsink.
In case of short the PSU would dissipate more than 350-400W (you have to take into account that the unregulated voltage must be higher than the maximum output one).
In another message you wrote that you would use it as battery charger or for a pump.
For such kind of load it would be better to use a switching PSU followed by one of those programmable switching regulators sold on ebay/alibaba/bangood...
I think the manufacturer is ruideng
here it is:
https://www.banggood.com/DPS3012-32V-12A-Buck-Adjustable-DC-Constant-Voltage-Power-Supply-Module-Integrated-Voltmeter-Ammeter-p-1065235.html?rmmds=search&cur_warehouse=CN
--- End quote ---
Also using a center taped secondary transformer for the pass transistor and a switch over circuit would save quite a bit on power dissipation.
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