Don't do that. You will destroy at least one of the amps. First of all test the power amp with a line out or ear phone signal (from a stereo receiver or similar) that you know is working. You can also shorten the input on the amp to see if it makes noice on the speaker.Considering I purchased a couple of those little amps to play with, what will happen if I wire two of them end to end? Such that the signal from the "receiver unit" feeds into one amp, and the output from that amp feeds into the input of another amp
Believe it or not, I also looked up the data on the IC; that was something I learned from your past comments when I was attempting to build the fuel injector trigger device. It seemed to look ok to me for what I wanted to do (well, at least as much of it that I understood).I checked the IC they are using and it has more than enough gain (80dB) to amplify the signal. The question is how they configured it on the board. If you have a schematic, it could reveal something. Do you have the volume control turned all the way up? Most amps are designed to achieve full output with 1 to 1.5 volts in because that is what most audio sources supply.
I figured it wouldn't work to connect two of the amps together. But the concept of adding a "pre-amp" might be a solution to the input being too low? I could look on AliExpress for a cheap pre-amp.Don't do that. You will destroy at least one of the amps. First of all test the power amp with a line out or ear phone signal (from a stereo receiver or similar) that you know is working. You can also shorten the input on the amp to see if it makes noice on the speaker.
I have similar setup for my bedroom TV. It has no Line Out signal so I am using the head phone output to feed an external Dolby 2.0 device with subwoofer. If you can't have your amp working, buy a cheap external computer speaker. They work with almost any input impedance.
If you can find the feedback resistor on that board, you might be able to increase its value to bump up the gain. The data sheet I found had a typical applications circuit with it. That is probably not too far off what they are using on the board. You might try feeding the amp with a different device (cellphone, computer, radio ...) to determine how much input is required to get the desired sound level. Then, you can compare that to the output of your intended device to see how much extra gain to add.Believe it or not, I also looked up the data on the IC; that was something I learned from your past comments when I was attempting to build the fuel injector trigger device. It seemed to look ok to me for what I wanted to do (well, at least as much of it that I understood).
Unfortunately there are no schematics that I can find for these amps.
Funny about the volume control. At first I assumed turning it clockwise would be full volume, like with every other electrical component I know of. So that's where I set it before the first test. No sound at all. Feared I'd installed it wrong, until I tried turning the control counter-clockwise. It's been on full volume ever since.
What language is this?If you can find the feedback resistor on that board, you might be able to increase its value to bump up the gain.
Electret mics require power to operate (they have a built in preamp) and will only work with the correct polarity. I think that is what they are getting at. If this amp will work with electrets, which don't necessarily have huge output levels, it should work with your .7V signal. I am actually wondering if you might be overdriving it. Maybe try it with the volume control very low and see what it sounds like, then bring it up slowly.Took a quick look on AliExpress for a preamp and saw this:
1.52US $ 23% OFF|Dc 5v-12v Micro Electret Amplifier Mic Condenser Mini Microphone Amplifier Board - Operational Amplifier Chips - AliExpress
Smarter Shopping, Better Living! Aliexpress.comwww.aliexpress.com
But in the description it says something that caught my attention:
"Amplifier board IN and GND use shielded cable access electret microphone, access to the attention of the polarity, the electret after the reverse will be very little or no sound"
By my translation, it says if the polarity of the input leads is reversed, then you may get little or no output. Could this be possible on my existing setup? I would not think so, but can't say for sure. I'm assuming in the quoted description the polarity issue is only when a "electret microphone" is the input source?
That comment reminded me that the 'receiver unit' (as described in my first post) has a volume control. In the original configuration that increases or decreases the volume to the little onboard speaker. In the modified configuration it would control the signal level going into the add-on amp. This is one reason I thought I could connect the receiver directly to the amp, with the receiver acting similar to a preamp. I set the receiver's volume to the highest level before doing anything else (I'll double check to make sure it is still at max), but apparently that still isn't enough. However if I add a preamp between the receiver and the external amp, then that volume control on the receiver should allow me to lower the input to preamp if needed (i.e. it's being overdriven).I am actually wondering if you might be overdriving it. Maybe try it with the volume control very low and see what it sounds like, then bring it up slowly.