Senco Model PP2 Meter

Like this Senco PP2 ? It's not really a "meter". It's a "Peak to Peak Comparison Meter", whatever that means.

What's inside: I couldn't find a manual or schematic. I have only some bad guesses as to what it does and how it works. At least you didn't pay any money for it.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

Looks like a fine paperweight.

Doesn't "peak to peak" imply a ratio of 2.828 wrt RMS? (So long as we are looking at a sine wave.)

MIke.

To be useful, the p-2-p meter should sample and hold the top and bottom values, and not simply measure RMS and multiply. If we measure p-2-p with a scope we get a stable trace, and then actually find the highest and lowest voltages.

Note that the 1.414 factor between RMS and peak voltage only applies to a sinusoidal signal!

It is incorrect for other signal shapes.

For instance, a square wave's RMS is the same as peak.

(Peak-to-peak is twice peak, so the factors double: p-2-p/RMS is 2.828 for sinusoidal, 2 for square.)

I think it is a curve tracer of some sort.

Is that a line cord soldered to the metal can of the potentiometer?

Nasty.

Is the line cord polarized?

Did the Senco company get sued out of business by the widows?

John ;-#)#

--
(Please post followups or tech inquiries to the USENET newsgroup) 
John's  Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9 
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games) 
                      www.flippers.com 
        "Old pinballers never die, they just flip out."

No , it is soldered to a terminal strip tab that is embeddeded in phenolic resin paper. The tab that is soldered to the potentiometer case is also connected to the phenolic strip. There is electrical isolation between the two tabs. It was a very common c practice in the 1960s.

--
This email has been checked for viruses by Avast antivirus software. 
https://www.avast.com/antivirus

I was wondering, the photo looked like it was soldered oddly.

Thanks for clearing that up!

John :-#)#

--
(Please post followups or tech inquiries to the USENET newsgroup) 
John's  Jukes Ltd. 2343 Main St., Vancouver, BC, Canada V5T 3C9 
(604)872-5757 or Fax 872-2010 (Pinballs, Jukes, Video Games) 
                      www.flippers.com 
        "Old pinballers never die, they just flip out."

r

I have a current probe , hall effect , that claims to be true RMS. When loo king at the fine print it says it is true RMS providing it is a sine wave?? If it is a sine wave then who needs a RMS mater. This is somewhat like a U SB powered speakers for a computer claiming 100 watts of power. That would be 20 amps at 5 volts , extremely unlikely. In the old days they would not lie like this just to make a sale.

Someone who only has a DC meter, and wants to measure AC.

In many situations we know we have a sine waves; we just want to know how big, as an RMS figure.

For instance, I can stick my here handy multimeter into the wall, configured for AC, and it tells me that the line voltage is 118.7. That's an RMS (predicated on it being sinusoidal), and it is useful. If it is true RMS, and accurate, then I know that the peak voltage is 1.414 times that, or 167.9, and peak-to-peak is twice that.

But there isn't any condition under which the speakers can continuously deliver that much power without a source other than the USB port; no USB host chip provides that much current. Thus it is unconditionally a lie.

Oh, if we pull out some old Popular Mechanics issues from, say, the

1940's, we will see all sort sof snake oil.

** A clue is the graphic on the front of the unit - it shows a typical sweep waveform from a TV set. TV service manuals are often full of such diagrams, accompanied by p-p voltage values.

A service tech might need to measure the ones he finds in a set, but has not got a calibrated scope - just a basic CRT based waveform monitor.

So he uses the Senco to produce a 60Hz sine wave with the same p-p height on the screen of his monitor - then measures that with a regular multimeter and multiplies the result by 2.82.

A similar trick can be used when calibrating the vertical display of a scope using just a DC source and a DMM. Set the scope to DC coupled and apply a voltage to the input while monitoring same on the DMM.

Most DMMs have better than 1% accuracy on DC volts so you simply adjust the scope's internal cal trimmer to match the full scale deflection ( usually 8 divs ) on the screen.

Square waves can then be used to check the scope's vertical response for flatness.

.... Phil

Thanks Phil, that makes sense... I was scratching my head, wondering what this would be used for.

George H.

m o

for

Yes but in my case I needed to evaluate the power consumption of a 2000 wat t LED display board. The current for this puppy is spikes of current off th e top of the hydro sine wave from all the DC switching power supplies for t he sign. This means a peak detector of the current is the wrong answer. For this reason I bought a true RMS current meter to average out the net curre nt to know what the breaker should be for the sign. You can imagine my disa ppointment when I read the small print that said true RMS provided it is si ne wave current. Root Mean Square has a precise meaning and a cheap peak de tector divide by .7 is not it. I am just ventilating but it really ticked m e off when I found this out the hard way. Worse the biggest letters on this current meter was TRUE RMS. To give this balance it could have been market ing without the support of the engineering. Just the same when those engine ers saw the final product with TRUE RMS bigger than life they knew it was a lie. To give this balance again I still use this little current meter and it has a added benefit of measuring DC current as well being a hall effect type meter. And it only cost 50 bucks so you really can not complain other than the lie about True RMS.

I see your point. Basic human nature will not change over time.

I've heard that they changed their name to Sencore in 1957.