Would you be interested in a BPA-200 kit?

[tlmadsen]

max.power

Peranders

Sorry,didn't se you post before.

I have not tried to get max power in 4 ohm, since the biggest transformer I have used is 500 VA.........and you need something bigger to get max power in 4 ohm.
If this is importent to people I don't mind prallel two 500 VA transformers and give it a go when I have the time.
You need max power for how long ???................it will become a cooling problem after about a minut or so......

Thomas

 

[peranders]

A cool 500 VA toroid can take 200% for a couple of minutes at least. If you can test, please do so and tell us your results.

I can't either see the problem with americans buying not from USA. Things in a regular envelope and PayPal works 100% for me even to America. The only thing I notice (before I used Paypal) is that americans in general have problems with regular bank transfers which seems to be very easy in the rest of the world. It can be something with that americans aren't used to it. I don't know. How do you pay bills, creditcard?

 

[nobody special]

There definitely must be some kind of thing with Americans that is different from the way you Europeans are used to doing it. As far as I'm concerned (being an American) I would rather not buy something from overseas unless it is the absolute last option. I feel about the same for Canada. This has nothing to do with national pride or anything like that... I just haven't ever done it before. Maybe a fear of the unknown? That, and there are options if you get screwed by someone in the US. It's easier to get your money back. Shipping is definitely cheaper, no way around that.
I pay our bills by personal check. Is it different over there?

 

[theChris]

overseas shipping takes longer and costs more. if you'r paying $20 for a small PCB and $10 for shipping that takes a month, well, it kinda sucks.

just design for difference amplifers this will allow for a wider range of options - inverting, non-inverting, or a difference amplifer.

 

[theChris]

i posted a while back about tieing both inverting inputs and both non-inverting inputs together on the lm4780. any opinions on this?

 

[tschrama]

Hi all,

I glad to see so many responds, so I thought I put in a few more remarks too..

About the size of the PCB: well why not keep is as small as possible. 3.8 x 2.5 inches PCb cost 51$ c for 3 pcs at ExpressPCB.. If it can be made small .. (about 1.9x1.25inch) , such a size would be enough for 12 amplifiers .. less than 5 $ each.. that would be nice

http://www.expresspcb.com/ExpressPCBHtm/Costs.htm

Further more, how about that super-short-feedback-path??? I do not believe in it.. but why leave that oppertunity...

About DC-servo's: I think you can leave them ... the LMseries have very stable offset, which can be adjusted with the input resistors... If you use a unity-DC-gain topoly, offset can be made 1mV easely .. so two amplifier= 2mV max working in 2 series 0.22 Ohm resistors.. hmmm .. gives 4.5mA DC current hobbing between amplifiers.. no problem here

The AC gain should be close I think.. 1% error gives 2% error max between amplifiers.. 2% of 35V max out = 0.7 Volt.. 0.7 volt over 2 0.22 Ohm series resistors is 1.6A .. Too much.. because this will flow from one V+ to amp1 to amp2 to V- ( is that so?) and would give enormus power dissipation.. 1.6A over 2x35V = 112W.. CAN THAT BE RIGHT???? hmmm

the 0.22Ohm output series resistors can be 5% I think.. I don't care if one amp is taking 45% of the current (so also power) and the onther one 55% .. it shouldn't matter much...

ehhh .. yep that was it ..

Hope it helps.. else just ignore me..

Greetings,
Thijs

 

[theChris]

"Originally posted by Dxvideo
2-In the same app notes the power output table; for 4 ohms the BPA200 can drive 450W "Burst Clipping Power". What does is mean? Can we say it is RMS value or PMPO? So we can really get 450Watts / 4ohm? "
-from my understanding, the test conditions for this very much favor unrealistic numbers.

 

[peranders]

I pay our bills by personal check. Is it different over there?

Checks is Sweden is nearly "what did you say?" They are very rare these days. A majority(?) pays bills via internet banks.

I wonder how many (american) people really hesitate to order from Hugh in Australia if they really want his stuff. Is it really easier, really, to get your money back from american companies for americans, if you are screwed?

I have ordered cactus books from USA without any problems.

I think Mr Madsen will be happy to deliver pcb's also to americans but I think also there may be room for your project too. If you start you may see how big the interest is. I have got a huge interest for my implemetation but not enough to trigger anything. A power amp is little bit more expensive (and takes much more time) to develop so I'll stick with small things at the moment.

If a couple of people (>5) want to build it (before I do), send me a message and we can work something out.

 

[theChris]

yeah, next year i was thinking of going into the pcb industry, because i have access to a milling tool. i wasn't looking to make a lot of money off it, but i realised that most people won't pay $5 shipping on a $1 part...

also, generic PCBs are a little harder for GC becasue you have so many different opinions on components and this can change the size consciderably.

 

[Dxvideo]

Thanks for your close interest.. If I am not wrong; its very important to equalisation dc-offset in parallel processing so servo circuits should be there. %1 tolerance resistors are ok, because they have %0.3 - 0.4 tolerance in fact. And finally nobody believes that circuit gives 450W RMS...

Am I right?

 

[peranders]

also, generic PCBs are a little harder for GC becasue you have so many different opinions on components and this can change the size consciderably.

Have you checked my then? Any features missing?

DeLuxe version:

* Inverting or non-inverting LM3886, can be chosen
* Inverting or non-inverting input buffer, with or without gain, can be chosen
* Feedback network which can satisfy everyone, full gain at DC or gain of 1 using a capacitor in the feedback
* With or without DC-servo for both inverting or non-inverting LM3886, can be chosen
* Output filter, L//R, small handwound inductor plus a resistor.
* Inputfilter, lowpass and also highpass to block incoming DC-signals. You could also skip the filters if you want to. I recommend though to use a high frequency lowpass filter.
* Mute, the LM3886 is "dead" for a short time at power up, can be chosen.
* Bridge connection and the LM3886 can operate in inverting or non-inverting mode, can be chosen.
* Pcb for 2 separate channels, stereo, or one channel in bridge connection. It's possible to change mode easily with help from a jumper.
* Power supply be on the pcb with sufficient amount of smoothing capacitance.
* Stabilized power supply for the buffers. +-12 V is chosen (can easily be changed) so the amazing AD8620 can be used.

The pcb is made but never manufactured and tested.

 

[Upupa Epops]

PCB

Per, I have exactly the same (all function which you describe ), double sided PCB, but with LM 4780, PCB is not also maded. We are thinking parallel .

 

[peranders]

Want to show it?

 

[tschrama]

Hi DXvideo,

Thanks for your close interest.. If I am not wrong; its very important to equalisation dc-offset in parallel processing so servo circuits should be there. %1 tolerance resistors are ok, because they have %0.3 - 0.4 tolerance in fact. And finally nobody believes that circuit gives 450W RMS...

I really don't think you need a opamp-servo .. just get the voltage offset to 1 or 2 mV and you'll be OK....


450W rms ..

Instantaneous Peak Output Power

.. sure .. I don't believe that is stretching the thruth one bit.. 1 LM3886 can deliver 11.5 A peak.. and has 135W peak power.. read the datasheet.. 450W peak power will be easy occomplished.. for just a ms or so..... RMS.. that easy.. 1 LM3886 can is rated for 68W .. 4 LM3886 should be able to give 272W RMS ... I don't think that numver will be far off... needs a good supply offcourse

Greetings,
Thijs

 

[theChris]

peranders, your board seems very flexible, but will it accept 14/ watt resistors AND SMD resistors? what about 1 watt wire wounds... and for caps can you use 1" long film and foil as well as 5mm electrolytics...

for the buffers and servos, can you use single dual or quad opamps...

i don't think it's possible to satisfy everyone, thoguh i definately like the ideas you present. my GC design is looking like it is very adjustable as well. i'm pretty sure it'll be based on my hi3gc (high input impedance inverting gainclone) with 100k input inpedance. since i'm using active crossovers i figure i can do an inverting configuration without worries.

 

[peranders]

I thought about SMD but the average DIY'er can't handle it. I have chosen not to use big caps. I wanted a small PCB.

You're right, I can't satisfy everyone but rather many I suppose...

 

[Dxvideo]

I really don't think you need a opamp-servo .. just get the voltage offset to 1 or 2 mV and you'll be OK....

[/B]

-Without them, can we get 1 - 2 mV offset?

-For one channel, what kind of power supply we need?

-What can you say about BPA200's gain? As I can see its 21... So for 300W/4 ohm what is the input sensivity?

-Can we realise that circuit by 2xLM4780? It would be very compact... Any modification need?

-And finally, two LM3886s or (one) LM4780 in parallel, can that circuit gives 150W/4ohm RMS?

Thanx.

 

[jackinnj]

BPA Ap Note has been updated

the BPA Application Note AN1192 at National Semi has been updated as of June 2004.

jack

 

[Jean]

if there is going to be a pcb run for bpa-200 I am in for a pair

 

[peranders]

if there is going to be a pcb run for bpa-200 I am in for a pair

Why wait guys? "Das Modul" is there for you. If the price isn't of major concern why don't you buy Thomas Madsen's pcb?