Power Supply Question

[Tukkar]

me mabibili ka na multitap secondaries from 3v-12v....meron din 9-0-9...

[jyjc]

what if po pag 12-0-12vac yung transformer then ang need ko na output is 12vdc
after rectifier is mag x1.414 pa yun dba.

if you need 12vdc 12-0 lang gagamitin mo from trafo yung isang 12vac hang mo lang or unused.
apporximate 15-16v unloaded after retification. you will need voltage regulator for 12vdc output.

[TechG]

ok +1 sa mga tumulong.

yung 12vdc fan ba na pang Computer, ok lang magkabaligtad ang polarity basta 12v ang supply?
12v lang ba maximum nun? or pwede sa 15v?

[Gwenda]

Just take note when designing linear power supplies like this and you are concerned when your output will regulate or not.  Take into consideration the line fluctuation.  How low and up to how high the input voltage is, will affect what you get on your secondary.

If you are in a low line or brown-out condition, will your secondary be enough for the regulator's overhead voltage.  Most 78xx ICs need at least 2 volts over the rated output voltage ALL THE TIME to keep the regulation.

[Gwenda]

yung 12vdc fan ba na pang Computer, ok lang magkabaligtad ang polarity basta 12v ang supply?
12v lang ba maximum nun? or pwede sa 15v?

No.  Basta DC, polarized, sundin yung + & - .  Iba kasi mga PC fan motors, kung tawagin ay inverter o chopper circuits.  They convert the DC into AC in the motor.  They will not run backwards or run at all when connected in reversed.  Will work up to 15Vdc pero will warm up some ang motor.

[Tukkar]

better run them in lower voltages rather than exceeding the required voltage....para di masyado maingay lalo pag sa audio mo gagamitin...napipickup minsan nga amp yan kaya me humming..

[kaiky14]

kaya naman ung 15vdc kya lng masyadong maingay ung fan mo. tama c sir tukkar minsan nagiging dahilan pa ito ng pgkakaroon ng humming sa amp.

[Tukkar]

in my class a amps i use fans to help out the bulky heatsinks for cooling...i run them 15v or even 12v dc....from a original specs of 24vdc at di na sya maingay....

[kaiky14]

pero kung ang normal voltage na kelangan ng fan mo ay 12v. sure na maingay ung fan, dahil mas mabilis ang ikot nito.

[01110011]

pwede din yung 220v na fan gamitin sa amp para isolated talaga mula sa amp

[kaiky14]

masyadong maingay ang fan na 220v, pero ok na ok sya sa lakas ng hangin na nabibigay nya. magandang gamitin yan kung temp controlled.

meron ako dito 5pcs na 220v (nidec brand) pwedeng gamitin kung naiinitan ka at wala kang e-fan sa bahay :D:D

[01110011]

^yung magandang klase na fan like boxer, less noise, pwede din maglagay ng thermal switcher

[jyjc]

kaya naman ung 15vdc kya lng masyadong maingay ung fan mo. tama c sir tukkar minsan nagiging dahilan pa ito ng pgkakaroon ng humming sa amp.

kung isang trafo lang ang source, pero nakahiwalay ang windings ng supply ng fan
sa secondary affected pa din ba or possible pa din ba magkaroon ng humming?

[01110011]

kung isang trafo lang ang source, pero nakahiwalay ang windings ng supply ng fan
sa secondary affected pa din ba or possible pa din ba magkaroon ng humming?

yan ang ginagawa ng mga manufacturers like; sakura,konzert the supply for the fan is on a separate winding, wala naman humming, pero there are some instances na naghuhum sya kahit separate yung winding

[jyjc]

oh so mas ok parin talaga pag magkakaiba ang source trafo

[Tukkar]

oh so mas ok parin talaga pag magkakaiba ang source trafo

kung me mabili ka na 220vac na fan the better....yan ang gamit ko sa mga power amps ko...pero okay na rin na mag-iba ka ng supply trafo kung me pandagdag ka.

[Gwenda]

Nakabile ako ng 220V 5" fan sa DEECO.  Sunon ata ang mfr, only P185 complete with two plastic grills and a power cord.

I don't think that a good AC fan will be a source of 60Hz hum sa amp unless na ang placement nito ay nakatutok sa sa very sensitive part ng amp.  There are cheap ways to filter out 60Hz hum in amps, the best way I think is good circuit layout and grounding (GND).