# turning 220 v AC into 60 V DC

Discussion in 'The Projects Forum' started by Zanac-X, Sep 11, 2012.

1. ### Zanac-X Thread Starter Member

Dec 23, 2011
51
1
hey guys

so my project is to assumable words made out of LEDs of different colors and it turns out that i need at least 55v per word to light it at max bright so i realy have no idea how to do it but here are some thoughts that i realy need you help to evaluate :

1- using a transformer or converter (i dont know its name but it looks like the mobile charger but a little bigger)...is there really a 220-60v ?

2-helping me with a circuit that can do the job.

3-use a voltage divider maybe but im not sure its going to work

thanks very much

2. ### MikeML AAC Fanatic!

Oct 2, 2009
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Very rare.

I would split the strings of LEDs into series-parallel strings so you could start with something more common, like 28 to 32V.

No, very inefficient

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3. ### wayneh Expert

Sep 9, 2010
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5,341
Have you considered using a commercial LED light string, like Christmas lights or rope lights? They're quite inexpensive, and solve some of your problems.

4. ### ScottWang Moderator

Aug 23, 2012
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5. ### Zanac-X Thread Starter Member

Dec 23, 2011
51
1
well yes i have but it is not that good looking when you try to make words out of them and they heat up very much especially when have very little space between them .

im using common LEDs like blue LEDs with 3.6v *14 LED for example =50.4V

6. ### MikeML AAC Fanatic!

Oct 2, 2009
5,445
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Are you forgetting that you need to put a resistor in-series with each LED string? That resistor should drop a minimum of about 25% of the voltage applied to the string. Read Chapt 1 and Chapter 2 here: http://forum.allaboutcircuits.com/blog.php?bt=675

Split your 14 Leds into three strings of 5 ea (one would have 4 Leds). Now 5*3.6 = 18. Put a resistor that drops about 6V in series, and then you can power three strings in parallel from a 24V supply.

Last edited: Sep 12, 2012
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7. ### wayneh Expert

Sep 9, 2010
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OK, fair enough.
Cleaning up the wiring isn't going to help much with heat dissipation. That's going to be a problem to solve with any design.

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8. ### Zanac-X Thread Starter Member

Dec 23, 2011
51
1
thanks for the tip but i have read it before not just here but in my collage too but im not sure of anything and need to have the OK from you guys to proceed.

ok the thing is i have just went to shop some LEDs with my friend and i asked about my problem and a man said the same thing (to use an 24V source) and im very much ok with it but only one thing it will probably draw about 1.5A and that is a lot when compared with 300mA .

also i have bought a transformer 220V-60V custom made,i tested it and worked very well i just need to build the bridge and smooth the output for a good DC source .

the problem is im really not sure if its the right thing to work with 60V or make the current high

9. ### Zanac-X Thread Starter Member

Dec 23, 2011
51
1
also a big thank you to ScottWang for his photo which i really wanted but one thing is that its very hard to find 1:1 transformer so any advice about this will be great

thanks for your time that really means a lot to me

10. ### wayneh Expert

Sep 9, 2010
14,859
5,341
That should be just fine, and allow longer strings with lower total current.

I believe the TOS here, however, don't allow discussing DC circuits over 50V. I could be wrong. Rectifying 60VAC will give you over 80VDC, so be prepared for that.

11. ### ScottWang Moderator

Aug 23, 2012
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987
You said that you bought a transformer 220V-60V custom made, if the transformer is just ac to ac, like as 220Vac to 60Vac-0V, then it can also used to the circuit that I linked, because you are unnecessary to use the voltage over 100Vdc.

12. ### Zanac-X Thread Starter Member

Dec 23, 2011
51
1
well basically that is what i was thinking but is there any part of this circuit needs to be changed because we are changing the output capacity like the Q1,Q2 or the value of the capacitor ?

13. ### ScottWang Moderator

Aug 23, 2012
6,366
987
60Vac x 1.414 = 84.84 Vdc

output capacity can be use as 1000uf/150v,1500uf/150V,2200uf/150V, if you don't care about the ripple, then you can use 1000uf/150v or 1000uf/250v, if the wv of cap can over 150V is better.

Q2 is OK, nothing special.
Q1 can be use as IRF640A_Nch_200V18A_0.18Ω_Vgs=10V.
or CEFF630_Nch_200V10A_0.4Ω
The Vds needs over 150V, if can over 200V is better, it will more safety, then it's OK.

There is another way can be adjust the Voltage, Using LM317, as the page 2 shown below.
if you want to increase the output current, then you can reduce the R3 value.

http://www.tij.co.jp/jp/lit/an/snva583/snva583.pdf

Last edited: Sep 13, 2012
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