UPC1237 Speaker protection board: Current requirements

[Sadface]

Hi Guys,


I have purchased a UPC1237 speaker protection board for an amp I'm building.



Assembled Speaker Protection Board 30A for Audio Amplifier Amp Omron Relay Delay 699938379519 | eBay


I plan to use a separate 12v power transformer to power the board.


My question regards how much current is required to drive the board.



I've had a good look at the datasheet but I can't identify anything that looks like current requirements.
http://www.unisonic.com.tw/datasheet/UPC1237.pdf

 

[Ketje]

Allmost all current is for the relais, the IC needs very little.
The coil data says 77mA, so for two 150mA.
That's DC, to be on the safe side double it for AC.
So you need a 12...16V @ 300mA transformer.
Mona

 

[Sadface]

Thanks

 

[ivanlukic]

But uPC1237 has current output of 80mA, how can it power two coils at 77mA each? May be the coils are connected in series but than you need 24V transformer?

 

[R Dijk]

But uPC1237 has current output of 80mA, how can it power two coils at 77mA each? May be the coils are connected in series but than you need 24V transformer?

But that output can then drive a output transistor, then available output relay current is transistor dependable 😉

 

[ivanlukic]

But on the board from e-bay, from post 1, I don't see power transistor. I suppose that TO220 on the heatsink is 7812 regulator.

 

[jan.didden]

Indeed the description says there is a 7812 on board.

Jan

 

[Ketje]

But on the board from e-bay, from post 1, I don't see power transistor. I suppose that TO220 on the heatsink is 7812 regulator.

Transistor can be SMD, even on the back side, you can't see it.
Mona

 

[ivanlukic]

Sadface,

Is there a SMD transistor anywhere on the board, on top or bottom side of it? If there is a transistor, than this kit is probably best buy. Relays are good if they are not fakes.

 

[minek123]

On this kind of board, every single part will be fake, especially Omron relays.

Sadface,

Is there a SMD transistor anywhere on the board, on top or bottom side of it? If there is a transistor, than this kit is probably best buy. Relays are good if they are not fakes.

 

[jan.didden]

On this kind of board, every single part will be fake, especially Omron relays.

Interesting you say that. I have some genuine OMRON relays of the type shown in the pic, and they look quite the same as the ones in the pic.
The case has a very special shape. To fake those would surely cost more then the genuine relays I believe.

Jan

 

[minek123]

How much did you pay for them?
Most likely more than this whole assembled board with all these parts.

Interesting you say that. I have some genuine OMRON relays of the type shown in the pic, and they look quite the same as the ones in the pic.
The case has a very special shape. To fake those would surely cost more then the genuine relays I believe.
Jan

 

[Sadface]

Hi Guys,


No transistors or SMDS.


See attached for some photos.


Any ideas as to how one might identify a fake?




My thinking is as follows:

None of the caps are name brand - one is 100uf instead of 220uf as stated on the board itself - probably reused caps or whatever is lying around.

7812s are about 75c

Omron relays of the same type as about $4.75 from element 14.




Economies of scales seems to suggest they could use genuine relays and make these boards for the purchase price of $18 with some margin.


I also paid a premium for 'Omron' relays instead of Songle brand relays like on this one.
30A Dual Stereo Power Amp Speaker Protection Board w/ LED Display AC12V-16V | eBay

 

[minek123]

Economies of scales seems to suggest they could use genuine relays and make these boards for the purchase price of $18 with some margin.

Maybe they could, but why would they do it?
Knowledge of human greed (and economy) suggests that people will choose "maximum margin" rather than just "some margin".
This whole business is about margin, not about speaker protection.

 

[ticknpop]

I have this kit and board , the amp has 95 Volt rails,
i have a separate transformer to supply the 12 volt regulator , but how do I select the 2 series resistors to pin two 2 from the amp outputs. The pin 2 cap is 100 uf bipolar and 100 k to ground, the supplied resistors are 30 K - way to low if the amp ever went to 95 VDC

 

[rsavas]

pin 2 max I is +/-3mA
Look at p4 in the NEC/Renesas datsheet.
You could make a voltage divider, from the amp o/p to ground and the V tap goes to pin 2.

 

[nigelwright7557]

Sadface,

Is there a SMD transistor anywhere on the board, on top or bottom side of it? If there is a transistor, than this kit is probably best buy. Relays are good if they are not fakes.

Relays will probably last a lifetime if not abused.
At power up they switch no current.
Its only if the amp fails that the relay will do much work when the relay turns off on full power. I prefer SSR's for the job but they are more expensive.

 

[pitbul]

upc1237 will probably not hold 150mA needed for 2 realays long time.
I will upgrade the board with adequate transistor which can handle coil current.
this board relays are suitable to handle only 20A on 28Vdc, if there is failure on amp with much more supply voltage, relay have possibility to melt on switch off.

 

[Jorgesilva]

Hi my dears DiyAudio livres.
Anyone can help me giving some instructions for i can wiring this 30A Dual Stereo Power Amp Speaker Protection Board ?

30A Dual Stereo Power Amp Speaker Protection Board w/ LED Display AC12V-16V 2.0 699909331751 | eBay

This is the product i buy but i need some help to wiring the DC power into ir correctly.
What is the positive and negative (ground) in the terminal connectors AC/DC?
Can anyone help me?

Best regards.

 

[PRR]

Well, the board says AC. But I do not see a rectifier. Which means it maybe needs DC. And wrong polarity WILL blow-up the regulator.

If I could see the bottom of the board, how the power terminals connect to the first filter capacitor and the LM7812 regulator, I could guess a "most likely" polarity. But I do not trust ten-dollar products.