get ready to pull you hair out, crazy idea inside

[Hero999]

If the output waveform is 10V peak and the power supply is 40V only 10% of the power is being delivered to the speaker at that instant. If the power supply is only 15V 66.67% of the power is being delivered to the speaker at that instant.

The problem is if we run it from a 15V supply alone the output power capability will be significantly reduced.

This is where class H comes in, power is only taken from the higher voltage rails when it's needed.

The extra power supplies don't use that much power when idling, in fact they don't use any extra power if it's just a case of adding more taps to a transformer.

 

[audioguru]

The Philips TDA1562 amplifier IC for car radios uses class-H. It has a built-in supply voltage doubler and switches its outputs so that they use the 14.4V battery for low power and uses the doubled voltage for 55W output at clipping into 4 ohms.

 

[Thunderchild]

but was that meant for having a high power amp run on a lower than needed voltage supply or specificly for efficiency, if you want 10 V of the 40 V supply you use a pulse thats 25 % duty cycle but at 40 volts I thought thats what class D was about, all the power going to the load save for the resistive losses of the mosfets

 

[Hero999]

Nigel is right about class D being more efficient but I don't know about simpler. Class H doesn't need any switching above the normal audio bandwidth so the layout isn't too critical. Class D switches at a much higher frequency and layout is critical.

 

[Nigel Goodwin]

Nigel is right about class D being more efficient but I don't know about simpler. Class H doesn't need any switching above the normal audio bandwidth so the layout isn't too critical. Class D switches at a much higher frequency and layout is critical.

Look at what commercial high power amps use - mostly class-D - it's efficient, decent quality, fairly simple - and reasonably priced.

 

[Hero999]

I've never seen a commercial class D amplifier before.

 

[Nigel Goodwin]

I've never seen a commercial class D amplifier before.

Many in-car amplifiers, many PA amplifiers, many TV sets, many home stereo systems, it's really pretty universal these days.

 

[Boncuk]

Hi Thunderchild,

I see most of your dilemma is caused by not having a proper PCB-layout for the amplifier.

Here is a suggestion for a quick PCB to make. Use the layout I designed very close to the manufacturer's design (without mixing up OUT A and OUT B, and not connecting unconnected pins of the TDA2009 (pins 7 and 11 are NC, but connected to pin 9 on the layout))

Print the layout normally and tape it to a copper clad. Then poke holes through the paper into the copper surface. Use an EDDING400 (800 for finer traces) and connect the "holes" according to the layout.

Etch and drill the PCB and you'll be finished in no time with a functioning amplifier.

BTW, TDA amplifier ICs are pretty touchy and critical not only concerning PCB-layout, they behave strange if the bypass electrolytic cap is too large in value.

I used a TDA2003 with a 1,000µF bypass cap. The chip's idle current was tremendeously high. After reducing the cap to the recommended 220µF the idle current was OK.

If you are interested in a quick amplifier PM me for the Eagle files.

Regards

Boncuk

 

[Thunderchild]

Hi Thunderchild,

I see most of your dilemma is caused by not having a proper PCB-layout for the amplifier.

Here is a suggestion for a quick PCB to make. Use the layout I designed very close to the manufacturer's design (without mixing up OUT A and OUT B, and not connecting unconnected pins of the TDA2009 (pins 7 and 11 are NC, but connected to pin 9 on the layout))

Print the layout normally and tape it to a copper clad. Then poke holes through the paper into the copper surface. Use an EDDING400 (800 for finer traces) and connect the "holes" according to the layout.

Etch and drill the PCB and you'll be finished in no time with a functioning amplifier.

I'm not quite inderstanding your explanation, do you mean start with a coper sheet and scrape away the excess or do you mean to draw in the neccesary tracks ?

 

[Chippie]

draw the tracks on with a pcb pen or whatever American equivalent you guys have over there (my response is in no way meant to be offensive when I say American...)

I got it..I was thinking of a Sharpie...I think they are water proof arent they?

 

[Thunderchild]

so you mean a pen that will draw with copper to make the tracks

 

[Nigel Goodwin]

so you mean a pen that will draw with copper to make the tracks

No, you draw on the the copper backed board, then etch the board to remove the copper where you didn't draw. It's the normal way of making PCB's, some kind of resist where you want the copper leaving.

 

[Thunderchild]

ah so it still involves exposing the board to UV light and then developing it, all equipment i do not have, sounds like I'd better start looking around

 

[Nigel Goodwin]

ah so it still involves exposing the board to UV light and then developing it, all equipment i do not have, sounds like I'd better start looking around

No, no UV - just draw the tracks on the board, and etch it - you can paint the tracks on if you want, and that was the method used before etch-resist pens.

 

[Thunderchild]

right so I just draw the circuit on the copper sheet and then put it in the acid tank.

 

[Chippie]

Yes that's right....

Warm the Ferric solution in a microwave oven if you can...Dont over do it...5-10 secs should do...You dont need much and a small container will save a lot of etchant being needed..just a little more so the board is fully submersed...

Agitate it to assist the process...

Wash thoroughly and clean with some steel wool....drill holes and mount components...

 

[solis365]

theres plenty of home PCB making tutorials out there on the net.

if you have a laser printer and gloss paper, you can print the layout on the gloss paper (backwards) and then iron the toner onto the pcb and then etch. apparently permanent markers work too. you have to be careful of undercutting.

heres one link that explains the process really well, but there are tons of other resources!

YouTube - DIY Printed circuit board

if that doesnt work, try
**broken link removed**

theyre the same thing. hope im not breaking any forum rules by linking to that site. if so, sorry.

 

[Boncuk]

Hi Simon,

the method I described uses a water and etchant proof pen on the absolutely clean copper surface (no grease!)

Print the PCB layout mirrored and punch holes at every pad with the paper taped to the copper clad to avoid slipping. Use the print as reference to draw the connections (traces) between components.

Every part of the PCB not being covered with ink will be etched. The result (after etching) should resemble the traces on the paper. Start from the outer pads and work yourself to the center for better control.

Draw the pads large enough. There is enough space on the PCB. When the board is etched drill holes with the paint still on the copper. After drilling scrub off the paint using Scotch Brite or steel wool. (Edding is really tough.)

Boncuk