| Author |
Message |
unseen
Joined: 02 Feb 2007
Posts: 5
|
 11 Mar 2007 14:47 Need help with a VFD VUmeter |
|
|
|
|
hi,
I've got a stereo VFD VUmeter based on the AN6870N, which I would like to connect to the line out signal of a sound card, CD player...
From the data sheet, the IC can handle an input voltage between 0 and 8 Volts. I need some ideas to make this work, probably with an opamp with gain and an offset that pushes the line out signal in the 0-8V range. I'm not that familiar with opamps, so any help is appreciated, maybe a schematic with the right resistor values.
Many thanks!
|
|
| Back to top |
|
 |
abidr
Joined: 14 Feb 2007
Posts: 127
Helped: 6
|
| 12 Mar 2007 8:03 Re: Need help with a VFD VUmeter |
|
|
|
|
a normal line out would be in the range of 2Vrms, which should be in the range of SOA for the VU.
alternatively you could use a simple op-amp with unity gain having high input impedance, that would serve three purposes isolation of signal, prevent loading of line out stage, and limiting the current. Do add a 10K resistor in the signal path.
But then again you have to experiment to reach desired results..
|
|
| Back to top |
|
|
daviddlc
Joined: 11 Feb 2007
Posts: 99
Helped: 6
|
| 13 Mar 2007 23:31 Re: Need help with a VFD VUmeter |
|
|
|
|
I made one VUmeter, and I ended up adding a low pass filter to have the desire results.
Without the low pass filter the meter was very "jumping" due all the frequencies being measured.
Also this low pass filter can have a gain to adjust the output from the sound card to the input parameters of your IC.
Usually the op-amps work with +V and -V voltages, the one that I used uses a single power supply of 12 volts.
Let me know if you want the schematic.
|
|
| Back to top |
|
|
