Its another dull night in my room...

Bassblaster

Super Member
When i get bored things that shouldn't happen, happen...

IMAG0595[1].jpg

i got this bright idea of hooking up a 2000 dodge ram head unit, to a power supply, and hooking it up to my big mid 80's speakers.
Anyone else ever done this? you would be surprised how loud these damn things can get with about 10WPC.
I tried to scope the outputs just for the lolz but it has to have a suppressor or some other form of protection because everytime i touch clipping it turns itself down :confused:
 
I remember back in the 70's a buddy connecting a KP-500 Pioneer stereo for his car to a power supply converting dc to ac plugged into the wall and yes very loud.
 
In one of my previous careers, (process instrument repair), a common practice was to re-purpose an old car stereo to run off a 120VAC-12VDC power supply as a shop radio.
 
In one of my previous careers, (process instrument repair), a common practice was to re-purpose an old car stereo to run off a 120VAC-12VDC power supply as a shop radio.
Someone my dad used to know did exactly that. he drilled holes in his garage wall, mounted some 6x9's and ran a car head unit off of a power supply.
 
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I tried to scope the outputs just for the lolz but it has to have a suppressor or some other form of protection because everytime i touch clipping it turns itself down :confused:

The output stages of many car head units are BTL (bridged) so they can get somewhat decent power from 12V. If so, the speaker outputs are not referenced to ground.

Part of the problem could be the connection of the scope itself, if the outputs are floating and they get grounded though the scope.
 
The output stages of many car head units are BTL (bridged) so they can get somewhat decent power from 12V.
Yep. im aware. i tried to look at what chips this used but i couldn't see due to the mounting bracket in the way. and i didn't really feel like ripping it all apart.
As such, the speaker outputs are not referenced to ground. So, when you connect the scope leads you are shorting the outputs. Lucky it seems to have good protection.
Yep. knew that too lol. ive played with bridge amps before. TEA2025B anyone? it was a very popular IC when it was still being made.
You need to be careful using a scope for such reasons. Bad things can happen to gear, the scope, and or you when you create an short circuit through accidental/inadvertent grounding.
Thats why i actually removed the AC-DC-GND switch from my scope. my luck i would accidentally bump it into GND and not know it, touch to my my amps outputs and here would be me trying to figure out WHAT just happened.
 
The GND switch isn't the problem, it's the shield connection on the probes that can make the short.
 
I had one of these on the workbench in the garage of my parents' house in 1969 & 1970.

http://www.radiomuseum.org/r/united_1_983334_oldsmobile_1956.html

With 10' of wire stuck in the antenna connector and the antenna matching cap behind the front panel peaked up, at night I could easily pull in ( from 10 Mi. East of the Pacific Ocean, Lat. ~ 34 deg. N) WLS Chicago, Salt Lake City, St. Louis Mo. and some points in between. Wish (sound familiar?) I had hung on to it. With the P-P 6V6 amplifier and hooked up to an Allied Radio 12" coaxial speaker, near Hi-Fi sound. I ran it off an old 12V battery and Western Auto charger.

That wonderful radio was seriously much larger than it looks on paper.
 
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