Prezden, nice boxes - you must be giving them away as gifts?
Speaking of affordable amps: solid state class AB amps that sound really nice (50w and deep deep bass) can be made for fairly little cost. $20 kits on eBay or Aliexpress - just takes soldering and a dual rail power supply. The power supply is what gets most people but there are SS amps that can use a dual 19.5v supply using two SMPS laptop bricks. If you ever have a larger speaker and want to experience real bass it is capable of, give the bigger SS amps a try.
Speaking of affordable amps: solid state class AB amps that sound really nice (50w and deep deep bass) can be made for fairly little cost. $20 kits on eBay or Aliexpress - just takes soldering and a dual rail power supply. The power supply is what gets most people but there are SS amps that can use a dual 19.5v supply using two SMPS laptop bricks. If you ever have a larger speaker and want to experience real bass it is capable of, give the bigger SS amps a try.
Hi X- I really like these little guys for this project because I can find a 12V ps supply for under $5. I am still working on some bigger projects with 3116/18 but they cost so much more to build. I have sold a few of these little lunch boxes to pay for future projects.
I’m still amazed at all the stuff you keep posting. Thanks!
I’m still amazed at all the stuff you keep posting. Thanks!
The correct DH4 transistor arrived and I have another brand of TL431 - I may pop those in and try to get the correct resistor value while at it. A pot here might make sense to dial exactly what you want. I am now running a bigger heat sink (the original TDA7297 lunch amp one). I don't have a lower voltage SMPS though as 19.5v is probably too low?
You could try that smps but you'd have to check it for any drop, because it's so close to the threshold.
When I get a chance I will replace the shunt transistor, a new TL431, probably remove the two protection diodes, and then try the 19.5v smps brick. Although, a 24v smps, with the resistors reset to operate at 21v might be kind of nice. I am running fan-cooled heatsink so heat is not a problem...
No, I ran one at 23v for a week. That's not the point however. The way they design IC's of any type, the voltage limitations aren't due to heat. The switches simply degrade at too high of a voltage. If the heat is too high the insides melt and nothing works, obviously, but the voltage damages the working devices not the insulation/epoxy/whatever like heat does.
You can do it, but you might want to invent some way to plug chips in and out, as opposed to resoldering them as they go.
You can do it, but you might want to invent some way to plug chips in and out, as opposed to resoldering them as they go.
I never was able find a 12v brick at thrift stores. Its easier to find the 19.5 laptop power bricks.
What is the current reliable source for these amps? Are there any other options for the same money?
For lunch money, that's the only option available. I'm still running the lunch money amp, along with my custom design, and I'm content with my system, me currently living in a small dorm room. Do the mods and you'll be happy. Add a preamp and leave the pot out for best results.
PSUs for the first gen XBox aren't too hard to find. They have a modest 5v rail and a beefy 12v rail. The PSUs for the earliest hardware revisions can push almost 17A on the 12v rail. Later versions were closer to 10A, I think.
Last edited:
Decided to case the small amp today.
I repurposed a case that I used for a raspberry pi Airplay server. I made a smaller version with a Pi Zero and now I had a nice case for the tda7297 amp.
It's not yet finished, I need to add a soft power on/off circuit, and maybe even add a Pi Zero for Airplay use. There's some room left inside. Also I have to ground the case, and get better RCA connectors, isolated from the case. Right now I'm testing it's thermal stability.
The PS is a LT1085 application. The power transformer is a 14VAC/5A one, and the final voltage feeding the tda chip is about 16.4VDC. So far it sounds great, no noise, no pop at on/off.
I repurposed a case that I used for a raspberry pi Airplay server. I made a smaller version with a Pi Zero and now I had a nice case for the tda7297 amp.
It's not yet finished, I need to add a soft power on/off circuit, and maybe even add a Pi Zero for Airplay use. There's some room left inside. Also I have to ground the case, and get better RCA connectors, isolated from the case. Right now I'm testing it's thermal stability.
The PS is a LT1085 application. The power transformer is a 14VAC/5A one, and the final voltage feeding the tda chip is about 16.4VDC. So far it sounds great, no noise, no pop at on/off.
Attachments
Would your board work with a 5A 19V notebook power supply? How could I order the module including parts and soldering?Did you see the board you can get from me? It does require 21v smps, 24v battery, or 23-24v linear power. (I have great PSU board that's been going with it for linear)
I was looking through this thread and saw several mentions of a "linear regulated power supply" taking this amp to the next level. When I type "12v linear power supply" in on ebay I get linear switching power supplies. Are these the same thing? A Google search doesn't tell me much either. I am assuming it is a smps with a linear regulator to smooth out the noise?
This was the power supply I was thinking about getting:
Vision Mod DCH 100 Linear Switching Power Supply 3A 243WU12 50 60Hz 12V 2A A77 | eBay
Is this supply good or do you guys have another recommendation?
This was the power supply I was thinking about getting:
Vision Mod DCH 100 Linear Switching Power Supply 3A 243WU12 50 60Hz 12V 2A A77 | eBay
Is this supply good or do you guys have another recommendation?