Jump to content
Electronics-Lab.com Community

Audio meter with 1 watt Luxeons


Recommended Posts

Hi Everybody,
I am a newbie here.  I am looking to make a "giant" VU meter.  I took a piece of PVC pipe 3" in diameter and 5 feet tall.  I cross-drilled 2" PVC and mounted a 1 watt Luxeon star in the bottom of each tube.  Audioguru's sound level meter is exactly what I want, with the microphone input so I don't have to plug it into my stereo.  It does not have to be accurate, I just want it to "dance" to the beat.  I have attached a picture with the LEDs just hooked to a power supply.

What I need now is to adapt Audioguru's circuit to power the large LEDs.  They run on 3.84 volts at 350mA.  Since the LM3915 has regulated current output for LEDs, I assume I can hook a transistor (PNP I think?) up in place of the LEDs, which will switch the big LEDs on and off.  Can someone give me advice on this?  Be very specific, I am an electronics novice.

Thanks
CK1

post-19328-14279142775225_thumb.jpg

Link to comment
Share on other sites


Hi CK,
Welcome to our forum. ;D
You will need a power supply cabable of supplying 3.5A for your project. I haven't seen a 9V supply with such a high current so you can make one yourself from a 12V cener-tapped 5A transformer, a 10A pair of rectifiers and a 4700uF filter capacitor.

PNP transistors like a 2N4403 can drive your LEDs through a 12 ohm 2W current limiting resistor.. The resistors will get hot and need some air circulation because they will dissipate about 1.3W each.

Link to comment
Share on other sites

Depending on you power supply and how you wire them PNP will be the wrong type. In a "normal" switch configuration the middle letter of PNP or NPN denotes the polarity of the required power supply. As such a PNP transistor will require a negative voltage on the bae WRT the emitter to switch the transistor on. If you can provide a circuit of how yopu intend to hook it up it would help.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
  • Create New...