Electricians needed..

[sonique]

if i were to run 3 fans with 12Vdc, 0.1A each, wats the input voltage and current needed to run all 3 fans at maximum output...? (sorry, i've forgot all the basics.. )

[avant]

assuming that you are connecting the fans in parallel, the input voltage needed will be 12V and the total current through the 3 fans need to be at least 0.3A.

You can probably get a AC/DC adaptor rated at 12V and .35A

[wfc31]

No, u should get a DC power adaptor with 12V output, but with at least 0.7A current supply, u can also get a 12VDC with 1A rated easily at SimLim Tower.
Using a 0.35A adaptor supply to run a total current load of 0.3A, ur adaptor will work very hard, not a healthy way.

[tawauboy]

do note that there is a difference between a dc power adaptor and regulated dc power adaptor.
a 12v dc power adaptor will output anywhere between 12-18v dc depending on the current capability. these type of adaptor will provide 12v dc only at the rated current. this means that a 12v 0.5a dc adaptor will output 12v when the current drawn is 0.5a. if the load is using < 0.5a, the output voltage will increase. if current used is > 0.5a, the output voltage will fall below 12v.
a regulated 12v 0.5a dc adaptor will output 12v when load is using <= 0.5a and the output voltage will fall below 12v if more current is used.

[sonique]

i'm placing the fans next to each other and all the common live and gnd wires are connected to one common point respectively. so izit considered in series or parallel...?

[avant]

do note that there is a difference between a dc power adaptor and regulated dc power adaptor.
a 12v dc power adaptor will output anywhere between 12-18v dc depending on the current capability. these type of adaptor will provide 12v dc only at the rated current. this means that a 12v 0.5a dc adaptor will output 12v when the current drawn is 0.5a. if the load is using < 0.5a, the output voltage will increase. if current used is > 0.5a, the output voltage will fall below 12v.
a regulated 12v 0.5a dc adaptor will output 12v when load is using <= 0.5a and the output voltage will fall below 12v if more current is used.

so given a non-regulated ac/dc adaptor, should we still get one with rated current close to what we are drawing or should we get one that has a much higher rated current as wfc31 recommended, but that will mean a higher voltage being applied?

[avant]

i'm placing the fans next to each other and all the common live and gnd wires are connected to one common point respectively. so izit considered in series or parallel...?

all red wires together and all black wires together should be parallel.

[sonique]

ok, thanx guys....will source for a 12vdc, 1A in put source to be on the safe side...

[tawauboy]

so given a non-regulated ac/dc adaptor, should we still get one with rated current close to what we are drawing or should we get one that has a much higher rated current as wfc31 recommended, but that will mean a higher voltage being applied?

depends on what you want.
if you want highest cooling capability and are not concerned about noise level, get an adaptor with higher rated current.
else get an adaptor close to your requirement.

[avant]

depends on what you want.
if you want highest cooling capability and are not concerned about noise level, get an adaptor with higher rated current.
else get an adaptor close to your requirement.

hmm... i'm still curious about the comment made on that "Using a 0.35A adaptor supply to run a total current load of 0.3A, ur adaptor will work very hard, not a healthy way." care to elaborate?

[sonique]

hmm... i'm still curious about the comment made on that "Using a 0.35A adaptor supply to run a total current load of 0.3A, ur adaptor will work very hard, not a healthy way." care to elaborate?

i tink wat he meant was if u were to run a load current higher than the supply ratings stated, it will overwork or overload the supply adapter and may destroy or cause mishap on the adpater on the long run since it had been overworked...juz like humans, we will/may have a breakdown if constantly facing high loads or pressure at work or hm....correct me if i'm wrong...

[tawauboy]

always use an adaptor that has higher rating that what you require. about 20% spare capacity would be sufficient.
most of these unregulated adaptors uses 'thin wire fuse' as overcurrent protection devices. so if these adaptors are supplying more current that it is designed for, the fuse will break, rendering the adaptor useless.

[wfc31]

avant,
sonique answered your question, good explaination.

[avant]

thanks for all the clarifications! informative discussion for everyone