Lasonic TRC-975 Volume Level Indicator (LED modification)

[Superduper]

The point is that you are experiencing brightness variations due to a system designed to have consistent load characteristics (LEDs) throughout the 5 internal op-amps. There is no way to really fix that since blues naturally require about twice the turn on voltage of reds.

So best case and most likely scenario is that you will get varying intensity of the LEDS and the meter calibration of when each segment lights will change and become uneven.
Worse case scenario is the L1403 IC does not last very long and you risk blowing that IC.

Just an FYI.

"Most of the power consumed by the circuits is consumed within the IC. When lighting the five LED's continuously, make sure the Vcc does not exceed 9v. When using a higher power supply voltage, insert a resistor in series with the LED's to restrain the power consumed within the IC package".

Andy. The problem is that what they are referring to is a resistor in series with the power rail that feeds all 5 LEDs, and not individual LED's. Again, not a problem when all 5 LEDs have the same characteristic but sorta problematic when the 5 LEDs all are different. The IC sinks the LED's directly. So it needs to dissipate all the current that runs through it. Personally, I think it best to stay with same LED's. But I understand that might not look as good as you like. An even better alternative is to redo the board to provide true dual VU's instead of a mono (imitation stereo) VU.

 

[Megabass]

Yeah I think using the pots was the only real way to get them to even-out (especially in relation to the intensity of the Blue and Orange LED's). Probably not the ideal solution, I know! Just for the record, the LED's used here are rated at 2.0 to 2.2v / 20mA, apart from the Blue which are 3.0 to 3.4v / 20mA.

Even though it seems to be fine for the time-being, I think proper Stereo VU's would be great. I have some old Sanyo tape deck parts lying around that might fit the bill. I recall the VU from that was definitely Stereo with x2 IC's.

 

[Reli]

Damn.....some electrical geniuses up in this mofo.

 

[mellymelsr]

Very cool mod!!...

 

[MONOLITHIC]

So nice, I gotta say it twice... Very, VERY dope!!!

 

[hemiguy2006]

Awesome mod!
It really looks stock too.

 

[Lasonic TRC-920]

That's a cool mod, but sounds like a technical P.I.T.A.

Looks kick ass for sure!

 

[ECR206]

Very nice!

 

[Jboogie2384]

Man this would be a smoking hot mod for the CONION C-100f!!!!
Superduper what or which LED's would you recommend? I'm feeling the white colored ones with some yellow and red. Let me know!!

 

[hoffsta]

Nice Mod!

 

[chrygore]

ima goona do that with my scr8