Ceramic Vibration Sensor - UK Vintage Radio Repair and Restoration Discussion Forum

John10b · 12th Sep 2018, 7:18 pm

Not sure if this is the correct place, so mods please move as you see fit.
Recently I’ve been “playing” with some old ceramic cartridges and wondering if I could get them working again. So I took a look around and found on the RS site the above item, stock number 285 784. The spec states an output of 4v p to p.
Now this is the part I don’t really understand and I was wondering if someone could explain.
It says “operating frequency of 100 Hz / switching frequency of 100 Hz,” what do they mean, it’s not resonance frequency, is it?
Also I was wondering if any one has made their own pick-up cartridge?
Cheers
John
Ps there are some pics of a Sonotone Cartridge that I took apart on post about Base Response if any one would care to look at.

mark_in_manc · 12th Sep 2018, 7:46 pm

I don't know what they mean by that. Piezo accelerometers have a flat open-circuit voltage response with LF cut-off set by the pre-amp you use (which can be a fairly fussy hi-Z thing) and HF set by the resonance of the mounted device on the structure you're trying to measure. This resonance puts a peak in, and then the response (and, embarrassingly, I can't remember if this is in terms of voltage over x,u or a) drops off at 12 dB / oct. I think (again, shot memory) you want to operate on this slope with a crystal pickup, to correct for record EQ, and the resonance of the arm-stylus system would be set low at 15Hz or so as a result.

I think this has potential as a pickup - two of them as cantilevers with one of those triangle things bearing down on them with the stylus acting on the apex. Great project!

Radio Wrangler · 12th Sep 2018, 9:16 pm

If you look in the datasheet via the RS webpage it cites applications as vibration/stress sensors, phonograph cartridges and micropositioners.

Which all sounds very promising and sensible applications. Refreshingly free of the trend to claim everything is suitable for the internet of things.

However it then goes on to warn:

"This bimorph (EB-T-3200 Electrode is silver. You shall be stored or operated this bimorph at bad conditions, high temperature and high humidity and input DC voltage, which insulating resistance is lower, affected silver migration. Please use care storage and operation conditions"

and:

"In the case of changes in specification, propose beforehand and discuss separately"

So you have been warned!

David

12th Sep 2018, 7:18 pm	#1
John10b Nonode Join Date: Nov 2016 Location: Aberaeron, Ceredigion, Wales, UK. Posts: 2,887	Ceramic Vibration Sensor Not sure if this is the correct place, so mods please move as you see fit. Recently I’ve been “playing” with some old ceramic cartridges and wondering if I could get them working again. So I took a look around and found on the RS site the above item, stock number 285 784. The spec states an output of 4v p to p. Now this is the part I don’t really understand and I was wondering if someone could explain. It says “operating frequency of 100 Hz / switching frequency of 100 Hz,” what do they mean, it’s not resonance frequency, is it? Also I was wondering if any one has made their own pick-up cartridge? Cheers John Ps there are some pics of a Sonotone Cartridge that I took apart on post about Base Response if any one would care to look at.

12th Sep 2018, 7:46 pm	#2
mark_in_manc Octode Join Date: Nov 2011 Location: Manchester, UK. Posts: 1,875	Re: Ceramic Vibration Sensor I don't know what they mean by that. Piezo accelerometers have a flat open-circuit voltage response with LF cut-off set by the pre-amp you use (which can be a fairly fussy hi-Z thing) and HF set by the resonance of the mounted device on the structure you're trying to measure. This resonance puts a peak in, and then the response (and, embarrassingly, I can't remember if this is in terms of voltage over x,u or a) drops off at 12 dB / oct. I think (again, shot memory) you want to operate on this slope with a crystal pickup, to correct for record EQ, and the resonance of the arm-stylus system would be set low at 15Hz or so as a result. I think this has potential as a pickup - two of them as cantilevers with one of those triangle things bearing down on them with the stylus acting on the apex. Great project!

12th Sep 2018, 9:16 pm	#3
Radio Wrangler Moderator Join Date: Mar 2012 Location: Fife, Scotland, UK. Posts: 22,901	Re: Ceramic Vibration Sensor If you look in the datasheet via the RS webpage it cites applications as vibration/stress sensors, phonograph cartridges and micropositioners. Which all sounds very promising and sensible applications. Refreshingly free of the trend to claim everything is suitable for the internet of things. However it then goes on to warn: "This bimorph (EB-T-3200 Electrode is silver. You shall be stored or operated this bimorph at bad conditions, high temperature and high humidity and input DC voltage, which insulating resistance is lower, affected silver migration. Please use care storage and operation conditions" and: "In the case of changes in specification, propose beforehand and discuss separately" So you have been warned! David __________________ Can't afford the volcanic island yet, but the plans for my monorail and the goons' uniforms are done