then again, the model number could be gibberish: http://www.ebay.ca/itm/Xentec-Power-Supply-5-VDC-18-A-XP90-9505-/131878778216

Xentec Power Supply 5 VDC 18 A (XP90-9505)

These sorts of things were very common back in the day. Here http://www.farnell.com/datasheets/1596275.pdf are versions by Sola.

I was able to find similar Xentek XE models,but not the one in my posession. I was able to find an XE15-9, which like mentioned above can vary from 8-10V and 15W power I guess.

 

I think its something like this.
View attachment 122556

I agree. The only thing missing is that there should be a dot next to pins 1 and 2 (or next to 3 and 4) to indicate the coupling polarity.

 

I tried both the 220V and 115V connections and both are working fine. The output voltage can be varied from 7.8 to 10.8V. Its a constant voltage output.So, I soldered the connectins for 220V. Infact , the 220V leads(2&3pins shorted) can be used both on 220 and 110V and output is same.

 

That's what I guessed was the case.

As you get further in your exploration of this supply, not that there is a voltage adjust pot on the board. That might mean that the output is adjustable over a wide range, say 3 V to 12 V, or it might mean that it is supposed to be a fixed voltage (say 9 V) but that you have the ability to dial it in very precisely. Note also that it has a pot to adjust the overvoltage protection (OVP) threshold. There are a few ways to implement OVP so you may have to figure this one out through trial and error (or you might be able to ignore it and just treat the supply as not having OVP at all).

You are right the voltage when I fired up the supply initially was 9V,but it can be varied from 7.8 to 10.8V. Though I haven't touched the OVP pot yet. What happens if I vary the pot?

 

You are right the voltage when I fired up the supply initially was 9V,but it can be varied from 7.8 to 10.8V. Though I haven't touched the OVP pot yet. What happens if I vary the pot?

As I indicated, there are few different ways to implement OVP depending on what the intended application is. In some instances it acts like a safeguard to ensure that the voltage at the output terminals does not exceed some threshold amount and, if it does, to clamp it to that level or otherwise prevent it from going above that level. How that is done differs depending on the specific goals of the supply. You'll probably have to play with it to see how it behaves. For now I'd just leave it alone.

 

I tried both the 220V and 115V connections and both are working fine. The output voltage can be varied from 7.8 to 10.8V. Its a constant voltage output.So, I soldered the connectins for 220V. Infact , the 220V leads(2&3pins shorted) can be used both on 220 and 110V and output is same.

This is not surprising -- since the output voltage of the transformer is somewhere in the 22.5 V range (and that's RMS, not peak) the value when you have it configured for 220 V but are running it at 110 V is probably around 11 V. This is probably more like 14 V at the output of the rectifier, so that gives enough overhead for the regulator to work with. But note that as you load the circuit the unregulated rectifier output will fall and you may find that the regulation begins failing noticeably well before the designed current limit is reached. If nothing else, the ripple seen at the input of the regulator will increase much quicker and be reflected in the output voltage sooner. I'd recommend running it as intended.

 

As I indicated, there are few different ways to implement OVP depending on what the intended application is. In some instances it acts like a safeguard to ensure that the voltage at the output terminals does not exceed some threshold amount and, if it does, to clamp it to that level or otherwise prevent it from going above that level. How that is done differs depending on the specific goals of the supply. You'll probably have to play with it to see how it behaves. For now I'd just leave it alone.

Guess I'll leave it alone then.

 

This is not surprising -- since the output voltage of the transformer is somewhere in the 22.5 V range (and that's RMS, not peak) the value when you have it configured for 220 V but are running it at 110 V is probably around 11 V. This is probably more like 14 V at the output of the rectifier, so that gives enough overhead for the regulator to work with. But note that as you load the circuit the unregulated rectifier output will fall and you may find that the regulation begins failing noticeably well before the designed current limit is reached. If nothing else, the ripple seen at the input of the regulator will increase much quicker and be reflected in the output voltage sooner. I'd recommend running it as intended.

Okay. The main reason I decided to go with 220V is because if I used the 110V leads and accidently plugged into the 220V outlet its gonna be disaster. Once I absent mindedly plugged a 110V-30V,3A transformer to a 220V outlet and it was KABOOM!! in few secs.Learned my lesson!!

 

Okay. The main reason I decided to go with 220V is because if I used the 110V leads and accidently plugged into the 220V outlet its gonna be disaster. Once I absent mindedly plugged a 110V-30V,3A transformer to a 220V outlet and it was KABOOM!! in few secs.Learned my lesson!!

Which is why, in most of the world, the 110 V outlets and the 220 V outlets are so different that you can't accidentally do that. I can't even imagine the carnage that would ensue if we used interchangeable outlets here.

 

Which is why, in most of the world, the 110 V outlets and the 220 V outlets are so different that you can't accidentally do that. I can't even imagine the carnage that would ensue if we used interchangeable outlets here.

Well the dumb electrician who replaced the two 220V outlets in my room didn't have the 220V receptacle so he put a 110V receptacle there instead and put a "220V" marking with a permanant marker on the cover and it gradually faded though.I know its a bad idea but ever since then I always recheck what I'm going to plug into.

 

That's extremely dangerous. Some day you will forget. Someday someone else will plug something in wrong. Some day you will move and the next person won't even know about this. Someday someone is going to get hurt or killed -- possibly many people in the ensuring fire. It shouldn't cost much at all to put the correct receptacle in there.

 

That's extremely dangerous. Some day you will forget. Someday someone else will plug something in wrong. Some day you will move and the next person won't even know about this. Someday someone is going to get hurt or killed -- possibly many people in the ensuring fire. It shouldn't cost much at all to put the correct receptacle in there.

You are right that is very irresponsible of me. But its been a few years I've living in this apartment now that I know for sure which is 110V and 220V plus I have snipped and changed most of the 220V appliances or devices I use in my room to the flat blade 110V plug. But you are right before I move I must label it on the outlets properly or someone is gonna get hurt especially if its a room heater etc

 

There is a current limiting pot missing in the circuit.I have a 10K pot from an LM2596 with me.Was thinking of removing the fixed resistor and adding a pot because the max current of the power supply right now is just 3.2A(30W) for such a huge transformer and cap. Guess I gotta find its limit.