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need power supply schem for 230-24/12 1.5a
- Thread starter sherazi
- Start date
You'll want to use a 24V 80VA transformer with centertap. The cost is usually the same as for one w/o a centertap. Regulator circuits are abundantly described on the net.
I might, if you are so kind as to remove the ad's from your sig., or else you will be banned.
Thanks, that'll do. Yes, well, we all work somewhere don't we? 
http://www.allaboutcircuits.com/vol_3/chpt_3/4.html explains many rectifiers.
Halfway down the page you'll find a <Dual polarity full-wave center tap rectifier> which is the one you'll want to use.
Now, you didn't say if you needed it to be a regulated power supply or not, so I specified a regulated setup for you. If you don't need it to be regulated you can use an 18Vct 40VA transformer.
A complete circuit diagram with regulators can be found here.
You'll want to use L7812CV regulators for 1.5A capability, or L78S12CV for 2A (use the 79 series for the negative regulator). A +/- 12V supply does the same job as a +12V & +24V.
Heatsink each with a 10 degrees Celsius / Watt (or better) heatsink. Use mica sheets and insulating washers (or similar) between the regulators and the heatsinks. Observe the difference in pinouts between the positive & negative regulators.
http://www.allaboutcircuits.com/vol_3/chpt_3/4.html explains many rectifiers.
Halfway down the page you'll find a <Dual polarity full-wave center tap rectifier> which is the one you'll want to use.
Now, you didn't say if you needed it to be a regulated power supply or not, so I specified a regulated setup for you. If you don't need it to be regulated you can use an 18Vct 40VA transformer.
A complete circuit diagram with regulators can be found here.
You'll want to use L7812CV regulators for 1.5A capability, or L78S12CV for 2A (use the 79 series for the negative regulator). A +/- 12V supply does the same job as a +12V & +24V.
Heatsink each with a 10 degrees Celsius / Watt (or better) heatsink. Use mica sheets and insulating washers (or similar) between the regulators and the heatsinks. Observe the difference in pinouts between the positive & negative regulators.
You can connect the individual secondaries in series to make a 24V centertapped secondary. This will save one rectifier bridge and give 1V extra headroom.
But if you rectify them separately you can use positive (7812) regulators on both, and do the series connection at the regulated DC outputs.
You can also use two positive regulators (one 7812 and one 7824) like in this multi-output supply.
But if you rectify them separately you can use positive (7812) regulators on both, and do the series connection at the regulated DC outputs.
You can also use two positive regulators (one 7812 and one 7824) like in this multi-output supply.
i am really sory but i cant get the data as it needs log in ... can u give a direct schematic
what if i use this circuit
if i want to use a 7805 with 1he 12 v output to get 5v ... can i do that...
i think i should be able to because i checked the outputs by voltmetere in simuklation and found it be positive not negative
what if i use this circuit
if i want to use a 7805 with 1he 12 v output to get 5v ... can i do that...
i think i should be able to because i checked the outputs by voltmetere in simuklation and found it be positive not negative
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It seems I have privileges with some publication sites I didn't know about. Never mind, that diagram had 8 regulators and might just have served to confuse you.
Yes you can get 5V from the 12V. It's quite wasteful with power, but if you don't need very much current it's ok.
Your diagram has positive as common for 12 & 24 Volts. Is that a mistake or do you need that configuration?
Here are two diagrams as I see it could be done.
The first is connected in a rather unorthodox way but has the benefit of not risking damaging the 24V regulator by overvoltage.
The lower diagram is the usual way of doing it, but it requires the transformer to have a regulation of 12.5% or better. The from-to raw voltages I have noted are with mains +/-10% together with a 20% transformer regulation. The 42.8V no-load voltage with high mains would exceed the 40V max input rating of the 7824.
You will need very good heatsinks, especially if the mains is often high and it's to operate in a hot place.
(*) You can't draw 1A from the 5V at the same time as drawing 1.5A from the 12V. The limit is 1.5A being the sum of these two.
Yes you can get 5V from the 12V. It's quite wasteful with power, but if you don't need very much current it's ok.
Your diagram has positive as common for 12 & 24 Volts. Is that a mistake or do you need that configuration?
Here are two diagrams as I see it could be done.
The first is connected in a rather unorthodox way but has the benefit of not risking damaging the 24V regulator by overvoltage.
The lower diagram is the usual way of doing it, but it requires the transformer to have a regulation of 12.5% or better. The from-to raw voltages I have noted are with mains +/-10% together with a 20% transformer regulation. The 42.8V no-load voltage with high mains would exceed the 40V max input rating of the 7824.
You will need very good heatsinks, especially if the mains is often high and it's to operate in a hot place.
(*) You can't draw 1A from the 5V at the same time as drawing 1.5A from the 12V. The limit is 1.5A being the sum of these two.
Attachments
thanx alot, can i use the first circuit even without the regulators, as i dont need much regulated volatage for them... further ore i am driving photocell for obstacle detection from the 12 and 24 v, i would be using a switch to either connect a 12 v or 24v system. and the 5 volts goes to mcu... i think the ratings are sufficient,
I asked you previously if you needed regulation or not, and if not then I said you should use a 2 x 9V 40VA tranformer instead.
Your diagram has a common positive which is unusual. It's impossible for me to tell if that's ok on the basis of your sketchy information.
I suggest you use my lower diagram to be safe. Just omit the 12 & 24V regulators.
Your diagram has a common positive which is unusual. It's impossible for me to tell if that's ok on the basis of your sketchy information.
I suggest you use my lower diagram to be safe. Just omit the 12 & 24V regulators.
Resqueline : thanks for ur help...
i had a question...in most power supply pcb i found special sort of caps with transformr, (a ring wounded two coils as can be seen in the pics attached... )
,
http://jimson.com/jimson/products.asp?id=32
i had a question...in most power supply pcb i found special sort of caps with transformr, (a ring wounded two coils as can be seen in the pics attached... )
http://jimson.com/jimson/products.asp?id=32
Those capacitors and INDUCTORS (edit) perform a dual purpose. Firstly they help suppress noise on the power line from reaching the power supply. A more important purpose for a switch-mode power supply (like the one in your image) is to prevent high frequency noise from the regulator from reaching the mains and causing interference.
edit: I meant Inductors, not resistors.
edit: I meant Inductors, not resistors.
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Look here.
DR1, C1, and C2 on that circuit diagram are what you're probably looking at.
DR1 is a pair of inductors on a common core. Similar to a transformer (but used in a different way).
Another example, drawn in a slightly different way. In this example the capacitors are placed slightly differently.
DR1, C1, and C2 on that circuit diagram are what you're probably looking at.
DR1 is a pair of inductors on a common core. Similar to a transformer (but used in a different way).
Another example, drawn in a slightly different way. In this example the capacitors are placed slightly differently.
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