Electronic hobbies and discussion

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#81
Finished a headphone amp this afternoon to go with a new set of Sennheiser HD6XX I bought a week or two ago. Class A, enough current to drive just about any headphone you can throw at it. Ability to swap opamps to find a sound signature that matches your tastes. Pretty frikkin' killer. Not too many bumps along the way. I bought it partially assembled from a guy in the UK, so I had to troubleshoot a couple of problems with his work. To paraphrase Edgar Allan Poe, "Trust not for whom the lead flows, if not from thee." IOW, don't trust other people's solder work!

IMG_4832.jpeg IMG_4835.jpeg IMG_4907.jpeg IMG_4909.jpeg IMG_4960.jpeg
 
Joined
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#82
For shits and giggles, I made a pair of bucket subs. Couple of Home Depot 5-gallon buckets (orange is the new black) and Peerless 8” woofers. I’m floored at how these sound. I built them as a WTF project since the parts were cheap. Turns out they frikkin’ rock! And they’re quite the conversation pieces.

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Joined
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#83
For shits and giggles, I made a pair of bucket subs. Couple of Home Depot 5-gallon buckets (orange is the new black) and Peerless 8” woofers. I’m floored at how these sound. I built them as a WTF project since the parts were cheap. Turns out they frikkin’ rock! And they’re quite the conversation pieces.

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sick
 

4runner DOA

Hold my beer
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#84
For shits and giggles, I made a pair of bucket subs. Couple of Home Depot 5-gallon buckets (orange is the new black) and Peerless 8” woofers. I’m floored at how these sound. I built them as a WTF project since the parts were cheap. Turns out they frikkin’ rock! And they’re quite the conversation pieces.

View attachment 43511 View attachment 43512 View attachment 43513 View attachment 43514 View attachment 43515 View attachment 43516 View attachment 43517 View attachment 43518 View attachment 43519
That's awesome.
 
Joined
Nov 15, 2018
Messages
1,692
#85
Now I can make my own custom project chassis boxes using my 3D Printer.
IMG_20210806_114817683.jpg

"Mounting bosses" are custom fit to the electronic part... In this case, the battery holder. The circuit board, not shown, has its own custom dimension mounting bosses for it as well.
IMG_20210806_114952988.jpg

The 6-pin phone connector style jack fits perfectly snug.
IMG_20210806_115349323.jpg

Pretty happy I can finally make functional things with my 3D Printer. :thumbsup:
 
Joined
Oct 4, 2018
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#86
Been teaching myself PCB layout for a month or so. Learned some basics from an EE at work, but for the most part will do trial and error. KiCAD is free and ok-ish to use. Digikey will make unpopulated proto boards for really cheap. Everything is thru-hole to be easy to solder.

This board is the brains of the new headunit i'm slowly building for the truck. Takes 12V ignition input and 12V illumination trigger to interface with the audio DSP and run/dim all LEDs on the face depending on if the headlight are on. The momentary button built into the DSP's volume potentiometer will allow me to override the truck's IGN signal to power-off the audio DSP by pushing in the volume knob, like a stock radio.

PCB layout image.JPG

I see i left off the pulldown resistor for the tiny relay. didn't have a footprint defined . I think i can squeeze one on to at least try everything else out. Couldn't figure out the datasheet for a proper LED driver chip, so i'm going the sloppy way with a tiny mosfet, current limiting resistors and PWM from an Arduino mounted onboard. Could probably all be done analog, but I need the crutch of being able to program out my mistakes. Missing a few parts but it's coming along.

dk red board 1.jpg
 
Joined
Nov 15, 2018
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1,692
#87
Going to try to etch this board soon.

I've etched my own circuit boards before, but it has been a while.

Anyways, I have a really old Schematic CAD and Layout program, but it is more than good enough for what I do.
IMG_20211001_010412393.jpg

The slight overlap on the lower left is fine as it is going to be drill holes for "headers".

It is, more or less, this piece I had put together as a "proof of concept/prototype".
IMG_20200303_074626340.jpg
 
Joined
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#88
I just did the rearrangement of components and now there is no overlap even though that didn't matter in this case.

I had to keep the same areas of where certain parts went for a particular reason...

Anyways, much, much cleaner on the routing traces too and it matches the test piece made damn near 1-1. :thumbsup:
IMG_20211001_074416672.jpg
 
Joined
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#89
Static shock to my vintage stereo preamp last winter sent my phono preamp into convulsions and straightlined DC through my amp and blew both tweeters in my 35yo speakers. Photo of the smoked/melted voice coil on one of them. So I decided it was a good time to upgrade crossover components and replace the tweeter diaphragms with something a bit more modern. I usually prefer a soft dome over titanium, but goddamn if these old beasts don’t sound like a whole new design now. Was on the edge of ditching them. But the upgrades/repairs have renewed the love I had for them when I got them new in 1987.

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Joined
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1,692
#90
RB14_ROCK_project_annotated_p1.jpg
At work, every 3months we have to come up with something that would "benefit" the worker and/or company

Using Arduino as it is easier to interface with and a much cheaper alternative overall.

This proposal is to make a battery voltage/current monitor because when the battery is in the case there is no way to "connect to it" and observe what is going on. The flat pack contacts also make it hard to interface with. I came across a housing fixture that someone had made that was meant for a totally different purpose, but they abandoned it and it was going to get thrown away. I took it and it will work perfectly for what I need it for. All I have to do is build my circuit, write the code, and test. Each number below correlates with the above picture on what it is...

#1 - using this as a functional "test board" for now and will be moving on to building a standalone circuit after the basic functions are worked out

#2 - The max input voltage to the analog pin for the Atmel328 chip is 5V. This is a simple voltage divider that is compensated for any "spikes" when initially powered up as far as voltage is concerned. I can put a 30V input and the code compensates that input voltage through the voltage divider network down-to approx 5V... in this case, the voltage divider is set for approx 4V and gives me about a 1V cushion, which works for this application just fine as I've tested for that. Since it is 30V compensated, I only put 21V in (NOTE: coming from the charger) so I have more than plenty of room plus the 1V on top of that. So anyways, the code compensates the voltage input signal at the voltage divider to read the actual voltage.

#3 - about a 13V NiMh battery pack that is the ultimate goal to monitor

#4 - Unit Under Test (NOTE: what the battery pack connects to and in a sense is also being monitored on how it is performing with the battery pack)

#5 - Battery charger, which is also being monitored to see if it is working like it should just by simply monitoring the voltage and current readings

#6 - LCD display giving the real time voltage/current readings

#7 - DMM monitoring the voltage divider network and it should NOT exceed the approx 4V. Remember, 5V is max allowed voltage on the analog input pins and I compensated 4V as my max to give that little bit of wiggle room for startup voltage. That is the best way that I can explain it. :noidea: In either case, you NEVER want to design something at it's lowest/highest values. In this case, if I was to design it for max 5V on the voltage divider, I would likely burn the analog input pin of the microController.

As you can see, the LCD is monitoring approx 13.3V and the DMM monitoring the voltage divider is not even at 2V yet. I could put a better "circuit protection" in, but I'm working with what I have right now and this should be more than good enough anyways for what it is.

Essentially, I'm monitoring the battery, UUT, and charger when all said and done. I told my supervisor that it will be a very useful tool to have when finally completed.

Finally, the current reading on the LCD display is wrong because it is not physically connected to the unit as far as reading the current value and the code hasn't been "tuned" yet to give the correct reading.

So far, the voltage reading reads down to 1.5V (and lower actually) all the way up to the max of 30V. The accuracy is pretty steady at roughly +/-0.25V, which is very acceptable in this particular case. I could make the code more accurate, but I'm fine with these readings and again, more than acceptable accuracy.
 
Last edited:
Joined
Nov 15, 2018
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1,692
#91
So I was able to dial in and/or "calibrate" the voltage as well as getting the amp reading part working as well.

The voltage can be off within +/-0.25V and the current reading can be off within +/-0.010A as the ultimate readings are going to be in the xxV and xA range so the "small numbers" really doesn't mean much, but nice to have as accurate as possible anyways.

Bench supply that I'm referencing to...
IMG_20211018_145236450.jpg

My little project I'm making...
IMG_20211018_145626213.jpg

I'm pretty satisfied and will start putting together the circuit on perf board as a standalone circuit.

I MIGHT use a 16x2 LCD instead for other add on ideas, but not sure at the moment?

Annnnnnyways...
 
Joined
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Messages
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#92
Something went bonkers in the headphone amp I built last winter. One light last week I was listening to it with friends and the next day I woke up to it squealing away. Cracked the case and smelled my favorite hot electrons. Found my input stage was toast (opamp) along with a couple supporting power supply resistors. Rang them out and they measured well, so I just replaced the opamp with another. Music came back, which is a good thing. But the resistors continued to get hot and provide more smoke. So something else is wrong in there somewhere. Yet another winter project.

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