1000W Simple PA Amplifier

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#924
#925
Ali express are usually very cheap for anything they are agents for.
Their guarantee requires you to pay return postage if you can prove the items are not as described, i.e. not authentic.

I believe they don't accept PayPal so you don't have them in your corner fighting for a refund because of fraud.
 
#926
Aliexpress the company serves as the intermediary to resolve payments for bad or false items. I don't ship back - I show proof of a problem with photos or a video and have always gotten a good resolution. It is pretty safe and I can't complain at all. There are so many vendors so they actually aim not to get a bad review and will generally do what is needed to get you to be happy. All my small signal transistors (even 2SK170's), lateral FETs (K1058/J162), 1% resistors, diodes, caps etc have been good and work/measure as expected. My one case were some bad 2SC5200/2SA1943's and I received a refund without shipping back. Getting established with an account is a pain though - you have to setup your credit card with their Alipay system - but once set up - works very smoothly.
 
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#927
 
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#928
Stay away!!! Obsolete. (MJL4281A from Any Vendor). Dangerous to Health.

Does not satisfy ROHS.

May contain: lead, cadmium, mercury, hexavalent chromium, polybrominated biphenyl (PBB) and polybrominated diphenyl ether (PBDE) flame retardants and Others.

You should wonder how Ali and Jim can sell these for less then Digi and Mouser ?
 
#929
this is looks like on ltspice, can every body explain why the first sine seen distorted (sorry iam new for lt spice)
 

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#932
Use a length of enameled copper wire.
Use a AA battery as a mandrel/bobbin.
1mm wire is good for most small and medium amplifiers.
1uH would use 9 or 10Turns wound around the 15mm battery.
This would need ~500mm of wire.

The Output inductor needs a parallel resistor to damp the ringing, use 1r0 to 10r.
A value roughly half the impedance of your speaker load is usually close enough.
This L||R is one half of the Thiele Output Network.
The other half is the C+R (Zobel) going from output hot to audio ground

The Thiele Network C+R & L||R provides a load at very high frequency to help stabilise the amplifier and helps isolate extra capacitance of a connected load or speaker cable that can change the phase margin of the amplifier.
 
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#934
Art M said:
Stay away!!! Obsolete. (MJL4281A from Any Vendor). Dangerous to Health.

Does not satisfy ROHS.

May contain: lead, cadmium, mercury, hexavalent chromium, polybrominated biphenyl (PBB) and polybrominated diphenyl ether (PBDE) flame retardants and Others.
Click to expand...
You do not understand ROHS policy.

Stuff is not dangerous to **user** , nobody would ever allow that.

The problem ROHS tries to solve is what happens **after** you dump it because you have NO further use for it.
In that case it may contaminate the soil, water reserves, etc. , but that is a *very* different situation,nobody says it's a danger to user.
 
#937
Sorry everyone:

I already bought all small part resistor, small transistor, transformer and etched 2 x ba1200 pcb now i made some loss here its better if i aborted

The reason for aborting apex BA1200 is because of the transistor MJL4281AG/MJL4302AG is a bit pricey 260$ (digkey) it ships from USA. It is not worth the wattage gain for the $$ you can can get Orginal Japan Toshiba 2S5200/A1943 cheaply.

You can get this 2 pic of this for 220$ with orginal toshiba transistor:
Assembled 1500W Powerful amplifier board/mono amp board stage amplifer board-in Amplifier from Consumer Electronics on Aliexpress.com | Alibaba Group

Are there any bigger board i can get ready made?
 

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