Speaker Board Module DIY Kit 12-24V Relay Voltage Regulator Circuit Module 7812 UPC1237 for HiFi

This kit is ALMOST there. What this means is it is missing a Zener, terminals that DON'T fit the board, and probably the CHEAPEST LED ever ( not that this really matters, since it is only an LED and you don't REALLY need it. If it's buried in the confines of your amp, you can't see it anyway. Spend a quarter and get a quality one. ).The board is nicely manufactured. The layout isn't the best. Whilst hole placement for connectors is widely variable because of the plethora of choices out there, at least match it properly or don't send the kit! Alternatively, place an oval hole there instead and that will accomodate metric vs sae placing. But, foks out there, don't drill the plate-through hole. Bend the pins slightly and it will just barely fit ( depending on which connectors they provided ).The OTHER layout issues are the IC outline does NOT indicate which way the chip should go. Theoretically, the bevel should indicate something, but w/o the board matching or the typical dot on the part.... who knows?On the connectors included, these are so large that it is now impossible to use any mounting hardware since they almost occlude the holes.Another reviewer complained there was no heatsink. This may not expressly be necessary depending on how much difference between the 12V output and whatever you are feeding it. It's good practice, however, as you might change DC sources in the future and not remember how much overhead you gave it.BTW, you DO NOT need an AC supply for this. The diode bridge guarantees polarity.Also, THERE IS NO DOCUMENTATION ANYWHERE. You're on your own....

Functions as expected in my recently built power amp. I am very happy 😄.

The board works! Saved my speakers once already. The kit was missing two capacitors so I deducted two stars.

The media could not be loaded.  The speaker terminal blocks do not fit in the board holes. The board must have been designed for another style of terminal block. They also cover up the board mounting holes. The AC input terminal block is definitely used as it has solder and PCB feed throughs on its pins. The solder and feed throughs must be removed in order for the terminal block pins to be able to go through the PCB. I'll revise this review once I've had a chance to build the kit and test it.REVIEW: I have two mono amplifiers. One is my main amplifier and the other is my back-up. I've got an audio cable that plugs into a spare android phone and I am driving one amplifier with left audio and the other amplifier with the right audio. I have a speaker connected to each amplifier output to give me full stereo.My main amplifier has a special circuit that uses a UPC1237, speaker protection IC. This circuit is designed to keep the speakers disconnected at power on for around 3 seconds and then reconnect them once the voltages within the amplifier stabilize. This is to eliminate any surges into the speakers at turn on. The IC also monitors the amplifiers output and if one of the outputs shorts and applies a DC voltage greater than 0.8VDC to the speaker, the IC disconnects the speakers. The IC also disconnects the speakers at power down.It all works fine in my main amplifier, however my second amplifier does not have this circuit and while I can not detect a surge at power on, I can hear a distinct "pop" in the speaker when I turn the power off.There are pre-built kits as well as kits that you have to put together that you can add into most amplifiers. I purchased this kit from Amazon for $10.00. This kit can control (2) speakers, left & right.Initially the speakers are disconnected. Whenever I apply power to the board, there is a 3 second delay before the speakers are reconnected through a relay. At that moment, a blue LED lights to indicate that the speakers are live.At power down, the relays de-energize and the speakers are disconnected, preventing that annoying "pop".With the circuit powered up and with the speakers connected, by applying a DC voltage to the speaker input, simulating a power amplifier failure, when the voltage approaches 0.8VDC, either positive or negative, the relay is immediately de-energized protecting the speaker from being damaged.It's a pretty neat circuit. I also ordered a pre-built board, somewhat of a different layout that I am going to test and then I'll choose which board I'll install into my backup amplifier.Since the board works, I raised my rating from 3 to 4 stars. The terminal block layout on the board has a 0.3" spacing between leads. A phoenix 4 position 7.62mm header (P/N ‎1707043‎) would fit nicely (see pictures). The 7812 regulator does not come with a heatsink. Mounting hardware and Standoffs are not included. M3 screws and standoffs will fit nicely.I used a 120/240VAC transformer with a 15V-0-15VAC secondary. 12VAC just was too low to get a nice 12VDC output from the 7812 regulator. 15VAC gave me 17VDC into the 8712.

Wrong parts, missing parts, and absolutely no instructions. Because I am a tech, I was able to figure it out and supply the correct parts.

Good layout, easy build. Worked the first time😁. Going to install in a hundred watt amplifier build. Only problem was one relay had the solder terminal bent flat down. Because of poor packaging, tried to bend it back then it broke off😠. Had to spend some time to fix that before I could build it. But other than that it seems like a fine product. I would give it 5 stars if I didn’t have to deal with the relay.

This circuit is badly designed. Download and learn the datasheet for the IC before using. You have been warned!