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Old 22nd May 2008, 02:59 PM   #11
Electrons are yellow and more is better!
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Default Re: Re: LM49810 amplifier

Quote:
Originally posted by ttan98



I have a pair of the same amp y0u ordered, I think it is NOT a good idea to release to the public the commercial in confidence the circuit diagram that has been given to you. Did you get permission to do so?

The developer took many hours/days to come up with the circuit, intellectual property from the East is the same as from the West.
Where is the schematic diagram? So why this post? Notice also that intellectual property only exists in a few countries. You can't really protect ideas unless you get a patent or not reveal it at all.
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Old 22nd May 2008, 03:08 PM   #12
Electrons are yellow and more is better!
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Default Re: LM49810 amplifier

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Originally posted by Elkaid
I'm feeding 44VDC to the modules using conventional non-rectified power supply. Could it be the voltage too low ?
What do you mean non-rectified? Do you have + voltage as much as expected and a - voltage? 40-50 volts?
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Old 22nd May 2008, 03:40 PM   #13
ttan98 is offline ttan98  Australia
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Default Re: Re: Re: LM49810 amplifier

Quote:
Originally posted by larzman
Ttan98, pardon your poor English, but the way I have viewed this thread, there is no issue about violating any IP or copyright in Elkaid's posts. He simply showed a photo of a pcb assembly. Exactly how is that any IP or copyright violation?

Quote:
Originally posted by peranders

Where is the schematic diagram? So why this post? Notice also that intellectual property only exists in a few countries. You can't really protect ideas unless you get a patent or not reveal it at all.
Both of you came too late the schematic has been removed. It was shown in the 1st post.

Rw=15k is ok for even at 34VDc supply. I got my amp working. It is playing now.
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Old 22nd May 2008, 05:29 PM   #14
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Good, I'll hope the threadstarter also will get his amp working.

I might add that uploading copyright material isn't OK like a schematics, especially if it says so.
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Old 22nd May 2008, 06:26 PM   #15
Elkaid is offline Elkaid  Canada
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Quote:
What do you mean non-rectified? Do you have + voltage as much as expected and a - voltage? 40-50 volts?
Sorry, I meant non-regulated. Using 30 Volts transformer + diode rectifier + 40mF, I get around +44 and -44VDC

Quote:
Good, I'll hope the threadstarter also will get his amp working.
The amplifier is working (nicely) but I have no idea which value the bias is set at since I'm unable to read voltage across Re (0.22ohm 5W). (I get 0 mV)

I don't know if bias adjustment difference is supposed to be easily heard but in my case, there's no much difference between the bias adjustment potentiometer being rotated completely clockwise or counter-clockwise. No much effect on mosfet temperature neither.

Tonight I'm going to try reading the value with my 'scope or another multimeter. I'm beginning to suspect a faulty multimeter.

I'll keep you posted
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Old 22nd May 2008, 08:48 PM   #16
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You should check the bias circuit. The voltage across it should be 2 x Vgs = 5-7 V I should think if you have mosfets or 1.4-1.7 V if you have BJT's.
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Old 23rd May 2008, 05:26 AM   #17
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T1 -> 2SC5171 (base: -1.89V collector: 1.06V emitter: 2.45V)

The error is in the bias circuit. I'm pretty sure of it.

The voltage across collector emiiter should be 6-8 volt
Base-emitter = 0.62-0.67 V if you have made things right.

Are you really sure you have mounted this part right? 100% control over B E C? If you interchange C and E you will get a 5 V transistor with Hfe of 5-10. It looks like that.

The voltage across T1 is calculated like this:

0.65*(1+(RB1/(RB2+Rp)))

Take a real close look in the datasheet because the design is more or less a 100% blue print of it.

In theory 44 V rails give you:

(44*44)/(8*2) = 121 watts

In the real life you'll get less because of not being able to drive the mosfets into saturation. I'll guess you'll loose up 10 volts peak.
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Old 25th May 2008, 10:24 PM   #18
Elkaid is offline Elkaid  Canada
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Hi !

Here's some updates. I checked bias circuit and it looks ok to me. (Well, the components values seems ok and correctly placed)

I measured some values on T1

With Rp fully off I get on T1 :

B: -1.01V
E: -1.57V
C: 1.39V

With Rp fully on I get on T1 :

B: -2.19V
E: -2.72V
C: 1.62V

Quote:
The voltage across collector emiiter should be 6-8 volt
I only get from around 3V to 4.35V

Quote:
Base-emitter = 0.62-0.67 V if you have made things right.
I get 0.57V

I still get nothing across Re

I'm completely clueless.... Any suggestions guys ?
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Old 26th May 2008, 12:27 AM   #19
ttan98 is offline ttan98  Australia
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I have the transistor version of your kit, I manage to make to work. T4 & T5 are transistors.

you find turning the pot clockwise will change the voltages of the bases of T2 & T3. voltage of T2 can be increased pass 1.2-1.25V, similarly with T3 pass -1.2-1.26V, With this voltage, T4 and T5 will turn on.

Once you pass the above voltages the current on T4 & T5 will increase QUICKLY. Take care then.

If you CANNOT reach +/- 1.2-1.25V then something maybe wrong.

your version is no much different, you need to increase the gate and drain voltage pass certain point before the T4 & T5 will turn on. That value will depend on that model of mosfet, it varies from model to model. I don't know the value, ask the kit seller.
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Old 26th May 2008, 12:55 AM   #20
Elkaid is offline Elkaid  Canada
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Hello !

Thanks for the reply

Quote:
you find turning the pot clockwise will change the voltages of the bases of T2 & T3. voltage of T2 can be increased pass 1.2-1.25V, similarly with T3 pass -1.2-1.26V, With this voltage, T4 and T5 will turn on.
You're right... I can even reach values around +/- 2V. However, I measured a voltage difference between T2 and T3 base of about 200mV.

I don't know if that's an issue (yet)

Thank you for your help !
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