Peak-hold VU meter

mbates14 · 29th September 2005, 01:43 AM

I want to find a schematic for a simple VU meter with peak hold. (like those old cassette decks with an FL display that would hold peaks for a sec or two).

Im googling, but turned up nothing. Anyone help me?

mbates14 · 29th September 2005, 05:28 PM

oops, i think I posted in the wrong forum, so mods delete this, as I am going to double-post in the right forums. thx.

mbates14 · 30th September 2005, 03:24 PM

Anyone??

Cobra2 · 30th September 2005, 05:15 PM

Maybe look for an old equalizer or tape-deck schematic, or salvage the parts from such a unit?

Arne K

Nasse · 30th September 2005, 05:19 PM

How about a peak led that stays lighted for some time, as addon with analog meter

macboy · 30th September 2005, 07:10 PM

Take a look at the National LM3915. In the datasheet you will find schematics for a full-wave-rectified peak-hold circuit. With this type of circuit feeding the 3915, you will have a 10-LED bargraph with fast 'attack' and slow 'decay' (rises quickly but falls slowly).

moamps · 30th September 2005, 07:13 PM

Here is an idea:

1. Use the LM3916 as a log display.
2. Make two active rectifiers: VU and peak.
3. Make a CMOS oscillator at ca 50-150Hz.
4. Use a CMOS audio switch-selector (4016,66,4051,52,53) and synchronously switch (using the oscillator) dot/bar mode and source signal (peak/VU) on the LM3916 .

This method should allow you to get VU reading in the bar mode and peak reading in the dot mode.

Regards,
Milan

mbates14 · 30th September 2005, 10:36 PM

yea, thats kind of what I mean. The old 80s technics decks had the FL display that would hold that one anode where the peak was for about one second or two.

macboy · 3rd October 2005, 12:26 PM

Quote:

Originally posted by moamps
Here is an idea:

1. Use the LM3916 as a log display.
2. Make two active rectifiers: VU and peak.
3. Make a CMOS oscillator at ca 50-150Hz.
4. Use a CMOS audio switch-selector (4016,66,4051,52,53) and synchronously switch (using the oscillator) dot/bar mode and source signal (peak/VU) on the LM3916 .

This method should allow you to get VU reading in the bar mode and peak reading in the dot mode.

I also had the idea of using both a bar mode display and a separate dot-mode one to display the peaks. Your method would work but I think that it is needlessly complicated. Since the LM3915/6 has open-collector outputs, you can simply connect two chips to the same LEDs. That way either or both can draw current throught each LED, superimposing the bar display (for instantaneous level) with the dot display (for peak level).

mbates14 · 3rd October 2005, 05:04 PM

I got it to work using his method.

used a bilateral switch, an op-amp oscillator, and two op amp active rectifiers with different RC time constants.

It works, but the only thing I dont like about it, it wont hold the peaks for a nano second, and it will slowly fall.

If i use a bigger cap, it will hold the peaks, but take way to long to fall.

I want it to hold the peaks for 1 second, and fall very rapidly. Not hold the peaks for a nano second, and fall like turtles.

hmmm.

29th September 2005, 01:43 AM	#1
mbates14 diyAudio Member Join Date: Jun 2002 Location: non	Peak-hold VU meter I want to find a schematic for a simple VU meter with peak hold. (like those old cassette decks with an FL display that would hold peaks for a sec or two). Im googling, but turned up nothing. Anyone help me?

30th September 2005, 05:15 PM	#4
Cobra2 DIY ! diyAudio Member Join Date: Apr 2002 Location: Stavanger, Norway	Eq Maybe look for an old equalizer or tape-deck schematic, or salvage the parts from such a unit? Arne K __________________ Ars longa, vita brevis

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29th September 2005, 05:28 PM	#2
mbates14 diyAudio Member Join Date: Jun 2002 Location: non	oops, i think I posted in the wrong forum, so mods delete this, as I am going to double-post in the right forums. thx.

30th September 2005, 03:24 PM	#3
mbates14 diyAudio Member Join Date: Jun 2002 Location: non	Anyone??

30th September 2005, 05:19 PM	#5
Nasse diyAudio Member Join Date: May 2004 Location: Scandinavia	How about a peak led that stays lighted for some time, as addon with analog meter

30th September 2005, 07:10 PM	#6
macboy diyAudio Member Join Date: Oct 2003 Location: Ottawa, Canada	Take a look at the National LM3915. In the datasheet you will find schematics for a full-wave-rectified peak-hold circuit. With this type of circuit feeding the 3915, you will have a 10-LED bargraph with fast 'attack' and slow 'decay' (rises quickly but falls slowly).

30th September 2005, 07:13 PM	#7
moamps diyAudio Member Join Date: Oct 2002 Location: Croatia	Here is an idea: 1. Use the LM3916 as a log display. 2. Make two active rectifiers: VU and peak. 3. Make a CMOS oscillator at ca 50-150Hz. 4. Use a CMOS audio switch-selector (4016,66,4051,52,53) and synchronously switch (using the oscillator) dot/bar mode and source signal (peak/VU) on the LM3916 . This method should allow you to get VU reading in the bar mode and peak reading in the dot mode. Regards, Milan

30th September 2005, 10:36 PM	#8
mbates14 diyAudio Member Join Date: Jun 2002 Location: non	yea, thats kind of what I mean. The old 80s technics decks had the FL display that would hold that one anode where the peak was for about one second or two.

3rd October 2005, 05:04 PM	#10
mbates14 diyAudio Member Join Date: Jun 2002 Location: non	I got it to work using his method. used a bilateral switch, an op-amp oscillator, and two op amp active rectifiers with different RC time constants. It works, but the only thing I dont like about it, it wont hold the peaks for a nano second, and it will slowly fall. If i use a bigger cap, it will hold the peaks, but take way to long to fall. I want it to hold the peaks for 1 second, and fall very rapidly. Not hold the peaks for a nano second, and fall like turtles. hmmm.