plasma metering ??

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wilebee

Well-known member
Joined
Jun 15, 2004
Messages
390
does anyone make a 40 to 50 segment meter that one could build that is like thos really cool ssl meters ? Wil

Wilebee
 
thats very cool so I guess it comes down the led driver circuitry as to how it performs either vu rms or ppm Wil

Wilebee
 
Or you could do a combination display where the overall level showed standard VU and a single LED lit to show Peak that had a second or two of persistence.

I wonder if there is a published standard somewhere that describes the optimum ballistic characteristics of such a display. Anybody know??
 
If you backup to the top of the site, it looks like they have driver boards available as well. You could easily pick up the led and driver board and implement this fairly readily.

ju
 
[quote author="Carl_Huff"]Or you could do a combination display where the overall level showed standard VU and a single LED lit to show Peak that had a second or two of persistence.

I wonder if there is a published standard somewhere that describes the optimum ballistic characteristics of such a display. Anybody know??[/quote]

The LM3916 (or LM3915?) LED bar driver datasheet has some information and example circuits for VU and PPM metering.

You could switch between these two with a analog switch and switch the driver simultaneously (does this word exist at all ? ;)) between bar and dot mode. I'll see if i can dig up that schematic...

;Matthias
 
for real plasma displays take a look here:

http://www.g-mw.de/leuchtband.htm

don't know about the prices though.

it's the same company that made the well known german light-meter-units in the 50's.

the disadvantage is that you need a rectifier/logarithmic-amplifier for it. i'm just looking for such a schematic.

chris
 
http://www.helmut-singer.de - look under "Bauteile" for Vishay Dale PBG12201.

Direct: http://www.helmut-singer.de/stock/711900893.html

Datasheet: http://www.helmut-singer.de/pdf/vishaypbg.pdf

A dual plasma display for around us$6..!

I wonder if this works for our SSL plasma bargraphs?

Jakob E.
 
Yep thats it Roger,

I have been inquiring with PrimeLED as well and they wanted $425 for the 53 segment bargraph......I was going to buy one but I really wanted the facility to add other parameters to the display, especially for that kind of money.

They are used in the DangerousMusic gear too. I saw a bunch of Wohler gear a while ago and they look absolutely awesome in real life....they are really smooth displays.

You can buy directly from Wohler but they only sell them in a half unit rack at they were asking £350.....

I would love to get stuck into a project like this when I have the time, especially the phase metering one we discussed back at TT.

Cheers Tom
 
Wil,

I remember a topic a while back about RTW meters, I think Frank (NRG) was working on it??

Sorry, I have no idea about the plasma meters though.....

Tom
 
Plasmas are a pain. You need a nice HT supply (which you might have if you're building tube gear) but then you need a 6-step ladder driver, a master ballistics curve generator, and a comparator for each channel.

It's way tricky. I have six plasmas here, I'm trying to scrape together the balls to build a driver for them.

Keith
 
those gossen-meters i mentioned earlier have all the driver-stuff included. they just need a voltage between 0 and 200mV at their inputs. so you need a rectifier/log-amp before that.

and for such a schematic i am looking for. does anyone have one? or does one know wich telefunken-unit did this job, maybe kubi has it on his site?!...

chris
 
http://www.all-electric.com/schematic/quad-met.htm

this is a design for multiplexing the driver chips. That way you can trim just once for a bank of meters. I guess you could do 24 or so in one bank.

Mark
 
looks interesting - thanks verbos........

nasty website to read though..I feel like I've had a few brews after looking at that!

Thanks for the link.

Roger, I reckon the DSP for that AD chip will be written in C or ASM. I asked PrimeL.E.D for info concerning how to program it myself. They haven't been forthcoming with info. I do have a incomplete development paper they sent me but its really not very helpful.

Tom
 
> A dual plasma display for around us$6..!

Helmut-Singer is a surplus shop, right?

That plasma panel needs a pretty complicated drive system. It does not have enough pins for a simple drive system.

The ABG-12205 is the complete unit, display and driver that accepts 0-5V DC inputs. That's really what we want; however H-S doesn't have any (that I can find). PartMiner.com lists it, but needs an account to see prices and real availability, and $100 minimum. Google didn't turn up any other sources, so it probably isn't distributed or in-stock anywhere a DIY-er can buy 1 or 2.

"The ABG-12205 consists of a 5 phase dual linear plasma bar graph display, driver circuitry and an interface circuit. A DC/DC converter is also included to develop the necessary panel voltage."

"The display operates on the patented principle known as ?glow transfer?. The display has 201 cathode elements per column, of which the first element in each column is a ?reset? cathode. The remaining cathodes are connected in 5 phases where every 5th cathode is connected. The columns are scanned from the bottom to top by pulsing the reset cathode low, followed by sequentially pulsing each phase low until the top cathode is reached, at which time a new scan is started at the reset cathode. The anodes are energized starting at the time the reset code is energized until the desired display height is reached, at which time the anode is turned off for the balance of the scan time. The cathodes are refreshed at a 70 Hz rate so the scan appears to be flicker free."

Patented? It sounds to me like the 1950s neon-lamp ring-counter. Wire ten neon lamps, resistors and caps the right way, bop a common connection, and the glow jumps from one lamp to the next. You can see this in movies and pictures of 1950s lab gear, typically as a row of 6 to 10 circles with 10 numbered lamps per circle.

This scheme seems to break the ring and expand it to 200 lamps. Except I think each 5 lamps work in 5-phase to step the glow up the bar. When it hits the desired point, you stop driving it but a keep-alive electrode holds the glow. For "real time" display, you repeat the cycle 70 times a second so the updates are faster than the eye (and don't flicker-beat against 50/60Hz room lights).
 
Spot on PRR.

There is also a "bright-up" portion of the display, where the counter timing is slowed down by a factor of two, so that each segment is illuminated for twice as long, thus giving the appearance of a brighter section above say 0VU.

I can scan the overview, ramp and timing information from the SSL service manual if anyone is truly interested, but I have to say that on the SSL bargraph consoles, the metering is the part that most techs hate and curse most frequently. I also have the Neve VR version here and I can scan the schematic, but the SSL actually has numerous pages of text with diagrams which explain the complex theory of operation quite excellently.

-You don't want to try and DIY one unless you're really very good at this sort of thing... Be warned!

Keith
 
People, russian IN-13 working without any
pulsing 5 phase stuff. It just 13 cm neon lamp with third elecrode.
F@ck, but anyone don't manufacture them fro 80'...
 
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