Hello again,
I have a question. I have found the following transformer and would like to know if it would be useable for a single channel of LM4780, brian gt kit, or an lm3875 p2p amp? Could I series/parallel wire several of these to get the amperage I need?
High quality power transformer features 120VAC primary and 2 secondaries. One secondary is 24 VAC at 2amps and the other is 36VAC (center tapped) rated 750mA. Open frame with metal mounting ears and flexible color coded wire leads. Size about 2.35"L (without mounting ears) x 2.26"W x 1.96" Tall. Brand new made by EPEC transformer.
They are selling locally for 1.99 each so I thought it might be worth looking into.
They also have this transformer for 6.95.
High quality open frame transformer by Magnatek features standard 115VAC primary and 25.2VCT at 2amp secondary. Size about 3" long (excluding mounting tabs) x 2.5" high x 2" thick. With insulated wire leads.
Thanks for your advice,
John
I have a question. I have found the following transformer and would like to know if it would be useable for a single channel of LM4780, brian gt kit, or an lm3875 p2p amp? Could I series/parallel wire several of these to get the amperage I need?
High quality power transformer features 120VAC primary and 2 secondaries. One secondary is 24 VAC at 2amps and the other is 36VAC (center tapped) rated 750mA. Open frame with metal mounting ears and flexible color coded wire leads. Size about 2.35"L (without mounting ears) x 2.26"W x 1.96" Tall. Brand new made by EPEC transformer.
They are selling locally for 1.99 each so I thought it might be worth looking into.
They also have this transformer for 6.95.
High quality open frame transformer by Magnatek features standard 115VAC primary and 25.2VCT at 2amp secondary. Size about 3" long (excluding mounting tabs) x 2.5" high x 2" thick. With insulated wire leads.
Thanks for your advice,
John
Hello,
Thanks for your response. I have another question though, paralleling would give me an increase in current, but what equation can I use to figure how much? I am pretty sure it will not double, as in 48V and 4A. Also I was looking at the data sheets for the LM3875 and it has a power supply voltage rating of 70ma max, but an output current limit of 4a, so I take it I need to match my transformers to the output current and not the input current? Or is it better to have a larger availiable supply of current available? Also when building LM3875 my pcb calls for 1000u 50v caps, can I substitute larger caps of the same voltage rating such as 2200uf 50v???
Thanks again,
John
Thanks for your response. I have another question though, paralleling would give me an increase in current, but what equation can I use to figure how much? I am pretty sure it will not double, as in 48V and 4A. Also I was looking at the data sheets for the LM3875 and it has a power supply voltage rating of 70ma max, but an output current limit of 4a, so I take it I need to match my transformers to the output current and not the input current? Or is it better to have a larger availiable supply of current available? Also when building LM3875 my pcb calls for 1000u 50v caps, can I substitute larger caps of the same voltage rating such as 2200uf 50v???
Thanks again,
John
I found these at http://www.goldmine-elec-products.com/home.asp. They seem to have a pretty good selection of resistors and caps also. I was going to order 4 this week but they will only ship, I can't go pick them up. I am going to try Apache Reclamation again and see if I can find some toroids before I pay to have these shipped 6 miles.
transformer help
hey! I'm new here. I have just recently built an amp and I need a transformer for it. I was wondering how ( if its possible ) to step up the voltage from this transformer.
I have a transformer rated at 13.5 vac @ 5 amps.
is there a way to step that up to 40 volts DC @ ( ? amps ) ?
I know it will provide the 60 some watts I need for max output power. My amp is a TDA7264 built into a wallet tin. Its output power @ 22.2 volts +/- ( I adapted mine for single supply operation, so 44.4 volts) is 32 watts per channel (LOL , @ 10% THD *cringes* )
Currently Im using a 32 volt @ 940 ma ( .94 amp) printer psu to power it. It will put some major kick into my marantz sp1200's. I think Im only getting about 17 watts per channel max, the chip is rated at 25 watts per channel @ 20 volts =/- ( again, 40 volts single supply).
So.. is there a way to step up the 13.5 vac tranny I have to 40 volts @ a lower amperage? thanks LOTS for any help!
hey! I'm new here. I have just recently built an amp and I need a transformer for it. I was wondering how ( if its possible ) to step up the voltage from this transformer.
I have a transformer rated at 13.5 vac @ 5 amps.
is there a way to step that up to 40 volts DC @ ( ? amps ) ?
I know it will provide the 60 some watts I need for max output power. My amp is a TDA7264 built into a wallet tin. Its output power @ 22.2 volts +/- ( I adapted mine for single supply operation, so 44.4 volts) is 32 watts per channel (LOL , @ 10% THD *cringes* )
Currently Im using a 32 volt @ 940 ma ( .94 amp) printer psu to power it. It will put some major kick into my marantz sp1200's. I think Im only getting about 17 watts per channel max, the chip is rated at 25 watts per channel @ 20 volts =/- ( again, 40 volts single supply).
So.. is there a way to step up the 13.5 vac tranny I have to 40 volts @ a lower amperage? thanks LOTS for any help!
lol well thats the problem.. I have no clue where to get a 40 volt center tapped transformer, let alone a 40 volt single supply tranny 
. I would like to try useing the one I have ( if nothing for the sake of learning how to do it) plus being 16, I have a limited budget.. I mow my neighbors lawn once a week and get 20 bucks lol. I need to save up money for my 63 falcon too, it needs a tank and brakes before I can drive it to get a job. But oh well, I guess if theres no way to use this transformer and step up the voltage I'm gonna haveta find a tranny online. Hey Ive got a question too. The transformer poweres my creative t5500 inspire 5.1 and its rated at 75 watts RMS ( boo hoo... thats at 10% thd too so its not exactly RMS you stupid creative marketing dept!) lol sry, anyways, i calculated that the 13.5 volt 5 amp transformer is able to produce 67.5 watts of power, so not too far off from their 'RMS' ( really peak ) rating. Now the chips inside are TDA8947J's , 2 of them ,each run from 9-26 volts, nominal voltage is 18 , which is where it puts out 8.5 watts per single ended channel and 18 watts in the btl. My sats are rated at 8 watts rms, center 20 wrms, sub 22 wrms. Probably all at the same 10 % THD too. Its 22 volt ratings are a little nicer, 14 watts SE and 29 watts BTL, which would be closer to the ratings if they really are real RMS ratings. My question is that the chip is designed to run on a single supply, up to 26 volts, DC, not ac. I know the amp has a rectifier bridge on it ( yes, I like to take my stuff apart and see whats really in it ) so it converts it to dc. My question is, is there something on the circuit that ups that ac voltage to a slightly higher dc voltage with lower current? Ie, 18 volts or 22 volts.
Theoreticly, If you multiply the voltage by a variable, then devide the amps by the variable you get your voltage/amps. if you use 1.3 you get 17.55 volts @ 3.8 amps, and by 1.4 you get 18.9 v @ 3.5 amps, and if you multiply it by 1.5 you get 20.2 v @ 3.3 @ and by 1.6 you get 22.95 v @ 3.1 amps. and so on and so on. I noticed that there are a heck of a lot more chips on the board than your typical cheap computer speakers, most of them 8 pin dip's. I havent been able to identify some of them, but I believe some are voltage regulators, opamps , and dc volume controlls, as well as crossovers. I kinda got carried away here, I guess my question is do they use some kind of inverter or something to up the voltage and drop the amps while converting it to dc? or will 13.5 volts @ 5 amps converted to dc really power the chips to their rated output? can you do that with a chip, lesser voltage @ higher amperage? ( Im not sure on that one, I dont think its true but I'm just asking
)
. I would like to try useing the one I have ( if nothing for the sake of learning how to do it) plus being 16, I have a limited budget.. I mow my neighbors lawn once a week and get 20 bucks lol. I need to save up money for my 63 falcon too, it needs a tank and brakes before I can drive it to get a job. But oh well, I guess if theres no way to use this transformer and step up the voltage I'm gonna haveta find a tranny online. Hey Ive got a question too. The transformer poweres my creative t5500 inspire 5.1 and its rated at 75 watts RMS ( boo hoo... thats at 10% thd too so its not exactly RMS you stupid creative marketing dept!) lol sry, anyways, i calculated that the 13.5 volt 5 amp transformer is able to produce 67.5 watts of power, so not too far off from their 'RMS' ( really peak ) rating. Now the chips inside are TDA8947J's , 2 of them ,each run from 9-26 volts, nominal voltage is 18 , which is where it puts out 8.5 watts per single ended channel and 18 watts in the btl. My sats are rated at 8 watts rms, center 20 wrms, sub 22 wrms. Probably all at the same 10 % THD too. Its 22 volt ratings are a little nicer, 14 watts SE and 29 watts BTL, which would be closer to the ratings if they really are real RMS ratings. My question is that the chip is designed to run on a single supply, up to 26 volts, DC, not ac. I know the amp has a rectifier bridge on it ( yes, I like to take my stuff apart and see whats really in it ) so it converts it to dc. My question is, is there something on the circuit that ups that ac voltage to a slightly higher dc voltage with lower current? Ie, 18 volts or 22 volts. Theoreticly, If you multiply the voltage by a variable, then devide the amps by the variable you get your voltage/amps. if you use 1.3 you get 17.55 volts @ 3.8 amps, and by 1.4 you get 18.9 v @ 3.5 amps, and if you multiply it by 1.5 you get 20.2 v @ 3.3 @ and by 1.6 you get 22.95 v @ 3.1 amps. and so on and so on. I noticed that there are a heck of a lot more chips on the board than your typical cheap computer speakers, most of them 8 pin dip's. I havent been able to identify some of them, but I believe some are voltage regulators, opamps , and dc volume controlls, as well as crossovers. I kinda got carried away here, I guess my question is do they use some kind of inverter or something to up the voltage and drop the amps while converting it to dc? or will 13.5 volts @ 5 amps converted to dc really power the chips to their rated output? can you do that with a chip, lesser voltage @ higher amperage? ( Im not sure on that one, I dont think its true but I'm just asking
)
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