Peter Daniel said:
Actually I'm using 12 volt rails and use a dual intelligent charger from <a href="http://www.patcoelectronics.com">Patco</a>. Basically the "power" switch just switches the batteries between the amp and the charger.
If you're using 24 volt rails, then you could charge four batteries in two parallel pairs using the dual charger. Though ideally it's best to charge batteries singly.
se
Member
Joined 2002
Re: batteries
I've got both CSB and Panasonic 7.2 Ah 12 volt SLAs. Haven't really found any difference between the two. The CSBs I already had on hand after scrounging them from some API uninterruptable power supplies and later bought some Panasonics to compare.
se
vic said:
I've got both CSB and Panasonic 7.2 Ah 12 volt SLAs. Haven't really found any difference between the two. The CSBs I already had on hand after scrounging them from some API uninterruptable power supplies and later bought some Panasonics to compare.
se
Hi!
Take a look at this battery supply... and the item description at
http://www.thel-audioworld.de/module/akku/akku.htm
(German).
Expensive, but very nice way to do this battery stuff...
Bye,
Arndt
Take a look at this battery supply... and the item description at
http://www.thel-audioworld.de/module/akku/akku.htm
(German).
Expensive, but very nice way to do this battery stuff...
An externally hosted image should be here but it was not working when we last tested it.
Bye,
Arndt
Battery-powered supplies
I'd like to start a new thread on designing various power supplies. I keep getting asked to search the forum first. I have read all the posts (I think all) regarding this topic. I don't know how to start a new thread. I still think this warrants its own new thread.
Specifically, I'd like to discuss DIY charging units. The National Semiconductor site has some ideas on battery charges. I think that in this forum we could design some fancy units. For example. How about a hybrid that switches into a regular AC source power supply when it senses low battery power?
Vic
I'd like to start a new thread on designing various power supplies. I keep getting asked to search the forum first. I have read all the posts (I think all) regarding this topic. I don't know how to start a new thread. I still think this warrants its own new thread.
Specifically, I'd like to discuss DIY charging units. The National Semiconductor site has some ideas on battery charges. I think that in this forum we could design some fancy units. For example. How about a hybrid that switches into a regular AC source power supply when it senses low battery power?
Vic
Re: Battery-powered supplies
Hi!
If you click on "New Thread", take a look at the top left corner of the "New Thread" screen. There you will notics a small checkbox with a "Have you searched?" next to it. Check it, state your questions, and post the new thread...
Took me some minutes to figure it out, as well...😉
Bye,
Arndt
Hi!
vic said:
If you click on "New Thread", take a look at the top left corner of the "New Thread" screen. There you will notics a small checkbox with a "Have you searched?" next to it. Check it, state your questions, and post the new thread...
Took me some minutes to figure it out, as well...😉
Bye,
Arndt
with my zobel (10R+0.1uF) I still have 666kHz oscillation, but 10mV peak to peak
is this acceptable?
is this acceptable?
just completed my gaincone! using the attached circuit by peter daniel but with the OPA548. will post pics soon.
havent tried it with an input yet.
there isnt any buzz if i put my finger on the input connector, should this happen?
i soldered the current limit pin to -v, giving the max current limit, is this correct?
havent tried it with an input yet.
there isnt any buzz if i put my finger on the input connector, should this happen?
i soldered the current limit pin to -v, giving the max current limit, is this correct?
asymmetrical toroid
Hi Peter, Fedde and all you other regulars,
This thread makes for interesting reading and having ploughed thru the 100+ pages, i've picked up a lot (and forgotten some already too). Thanks for that. I want to start building my own gainclone soon, first based on OPA 541 and have bought a toroid to begin with. Problem is that it is assymmetrical. One sec gives 20 V and 13 A, the other sec gives 28 V at 1.5 A. I think the first sec is good enough to power a gainclone, but all the schematics posted here assume two secondaries. How will i go about it? Use diodes just like in one sec and then treat the outgoing current as + and -? And how do i get ground for the toroid (and does it need it, cos the 220 V mains in dont have ground either.)
OR should i unwind the 28 V secondary (like Peter did to lower the voltage) until get a 20 V sec. And is there some trade-off, like less V, higher A if i do so?
I searched for an answer on this site, but couldnt find one. I'm new to diy in electronics, so if these questions are stupid, please dont take offence🙂
greetz, Wasbeer
Hi Peter, Fedde and all you other regulars,
This thread makes for interesting reading and having ploughed thru the 100+ pages, i've picked up a lot (and forgotten some already too). Thanks for that. I want to start building my own gainclone soon, first based on OPA 541 and have bought a toroid to begin with. Problem is that it is assymmetrical. One sec gives 20 V and 13 A, the other sec gives 28 V at 1.5 A. I think the first sec is good enough to power a gainclone, but all the schematics posted here assume two secondaries. How will i go about it? Use diodes just like in one sec and then treat the outgoing current as + and -? And how do i get ground for the toroid (and does it need it, cos the 220 V mains in dont have ground either.)
OR should i unwind the 28 V secondary (like Peter did to lower the voltage) until get a 20 V sec. And is there some trade-off, like less V, higher A if i do so?
I searched for an answer on this site, but couldnt find one. I'm new to diy in electronics, so if these questions are stupid, please dont take offence🙂
greetz, Wasbeer
Peter have you came to any conclusions in regards to the sound of your opa549 based amp and your lm3875 amp?
thanks,
Ray.
thanks,
Ray.
I've been comparing both chips on and off all week on different music and at different times. It is hard to decide which one is better, but my impression today is that OPA549 seems to be more flat sounding and maybe more accurate, yet LM3875 somehow adds more life to the music and this probably would be my prefference. It's just that music seems somehow more real when listening to this amp. Like my friend said: "OPA549 sounds more like all the other amps", LM sounds a bit more "special".😉
hello,
I've got some 244k Vishay resistors . Will these work as well as a 220k for the feedback resistor? I don't know how crucial this spec is.
I've got some 244k Vishay resistors . Will these work as well as a 220k for the feedback resistor? I don't know how crucial this spec is.
Variac said:
It just sets the voltage gain of the opamp. Doesn't have to be very precise at all. Just can't be too low or too high. 244k isn't too high.
se
Re: asymmetrical toroid
Hi!
Look into the application notes from TI. The OPA541 (like all OPA power op-amps) can be run from a single supply:
"The OPA541 is specified for operation from power supplies
up to ±40V. It can also be operated from unbalanced power
supplies or a single power supply, as long as the total power
supply voltage does not exceed 80V."
This means, that the OPA simply needs a voltage difference between V+ and V-, and if you apply 0V and 29 V (the 20 V rectified), you will be on the safe side, but you will not get the maximum power rating out of this IC (that would be with +- 40V or 0 - 80 V).
This means, take only the stronger of your secondary windings, connect it to a single bridge, and connect the other two poles of the bridge to V+ and V- (with correct polarity, of course). It should work.
And maybe consider bying another transformator sometimes, since you will be wasting some power with this lower rated supply.
Bye,
Arndt
Hi!
Wasbeer said:
Look into the application notes from TI. The OPA541 (like all OPA power op-amps) can be run from a single supply:
"The OPA541 is specified for operation from power supplies
up to ±40V. It can also be operated from unbalanced power
supplies or a single power supply, as long as the total power
supply voltage does not exceed 80V."
This means, that the OPA simply needs a voltage difference between V+ and V-, and if you apply 0V and 29 V (the 20 V rectified), you will be on the safe side, but you will not get the maximum power rating out of this IC (that would be with +- 40V or 0 - 80 V).
This means, take only the stronger of your secondary windings, connect it to a single bridge, and connect the other two poles of the bridge to V+ and V- (with correct polarity, of course). It should work.
And maybe consider bying another transformator sometimes, since you will be wasting some power with this lower rated supply.
Bye,
Arndt
I was wondering what was a too high value for the feedback/input resistorsSteve Eddy said:
I don't mean what gain is too much, in example if you keep the same Rinput/Rfeedback, the gain will be the same
but there are certainly optimal values, and that's I want to know
10R/220R would be of in theory, 10M/220M too
but why do we use 10k/220k?
Bricolo said:
Basically you're considering two things. Input impedance and noise. As you get lower on the scale, the driving circuit is under a greater load. As you get higher, the loading is less but you get more noise.
An input impedance of 10k is an easy load even for tube circuits but it's not so high that it significantly increases noise.
se
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