Geller Labs
Geller Labs



Following our 2013 closing: Some sales will continue for a time, e.g. PPM kits, SVR kits (AD587LN), JCan kits, and MGTA kits are still available. PPM kits take a long time to pack and might need up to a week from order to shipping.

JCan kits and parts

The JCan project (AC Voltmeter, cable not included)

allows you to measure the Johnson (thermal) noise of a resistor in a home or school lab. Building the experiment is fun and interesting and creates a unique home lab instrument. Use our MS Excel calibration worksheet to convert your results directly into standard noise readings in nV/rt Hz . Instructions and project details can be found in the July, 2007 issue of Nuts & Volts Magazine . More information on resistor noise measurements can be found on our JCan References page. More information on measuring the noise bandwidth of a filter can be found in our nBW Technote. To perform the JCan experiment and use the JCan instrument, you will need an AC voltmeter that can measure between 1 and 40 millivolts AC. Most modern bench meters (DMMs) have a suitable AC voltage range.1

Overview: Once calibrated (two numbers entered into the Calibration Worksheet), plug a resistor into the RUT jacks (with the power jacks open), turn on the power, close the lid, and measure the output amplitude in mV AC. Plug that number into the worksheet and get a thermal noise value in nV/rt Hz for that resistor. The blue worksheet curve represents the theoretical Johnson noise curve at no current. The green curve shows how your measured data falls on the curve. Finally, use two like valued resistors, one in the RUT test jacks and one in the resistor power test jacks, to see how the noise changes for different types of resistors under power (e.g. metal film as compared to carbon composition). Use the parallel value of the two Rs and plot a corresponding noise point above the Johnson noise curve. If you have an audio spectrum analyzer or a FFT capability, observe how the 1/f noise for a pair of carbon composition resistors is much higher than for other types such as metal film resistors.

Schematic diagram, what's inside the JCan?, Parts List, Calibration Worksheet, JCan project files: zip

This page changes often. Please hit "re-fresh" or "F5" on your browser to be sure to be looking at the most current page.

There will be a limited number of kits, parts packs, and assembled JCans available in this first run as we judge interest in the JCan product line.

JCan Kit (quantities are limited, but still in stock): $64.95 A kit of all parts to build the JCan shown in the article. The kit includes the JCan PCB, all semiconductors, resistors, capacitors, pins and sockets, an undrilled 1/2 gallon can and a resistor "cal pack" for calibration experiments: (two 9V batteries2, BNC cable, AC voltmeter not included) (For European Union (EU) buyers, the kit is not RoHS compliant) Please add the cost for shipping 1 pound 1 ounce, in the U.S. from zip 13492 to your zip (Priority Mail). We tried to keep the package under a pound for standard rates, but there is just too much stuff in the can :)

Please see our Ordering page for payment options. We accept university purchase orders.

Assembled and tested JCan $269.95 with calibration data including a bandpass plot and completed JCan Worksheet with measured nBW, noise floor, gain, spare front end JFets, spare gold posts, and a printed copy of our JCan article (two 9V batteries2, BNC cable, AC voltmeter not included) . Please add the cost for shipping for 3 pounds (16" x 10" x 8") in the U.S. from zip 13492 to your zip (Priority Mail) (Allow up to one to two week delivery times from day of order. It takes about 6-8 hours to assemble and fully test a JCan with calibration data).

JCan PCB $8.95

Gold Jack Pack $5.95 (four gold slit jacks, 9 gold MillMax pin jacks, 2 IC sockets gold insert/tin pins)

Resistor Cal Pack $2.49 (fifteen 1% metal film)

For a few small packs add $2.33 for First Class shipping in a small box in the U.S. (or, $5.35 for Priority Mail for quicker delivery).

All checks and money orders should be made payable to "GELLER"; please see our ordering page for more information.

Sales to EU electronics hobbyists and Amateur Scientists: Some parts of the JCan kit and assembled unit are not RoHS compliant. While we cannot actively market a non-compliant item to the EU, we have written advice from the RoHS UK authority, that it is permissible for EU electronics hobbyists and Amateur Scientists to purchase one unit for their own hobby use so long as it will not be used for their commericial gain by re-sale in the EU. EU buyers should contact us please for shipping prices. Modest cost shipping cost to the EU can be accomplished by using International First Class Mail.

Prices reflect our cost in ordering parts from various distributors and the time to make up the packs and kits. It is very time consuming to prepare many of the packs. In doing cost comparisons, remember to account for the shipping and handling charges charged by each distributor. We charge only the actual USPS postage (we do our best anyway, occassionally an estimate is a little high or low), with no charge for a sturdy shipping box (from Associated Bag or Uline) and no additional handling charges. Our very modest profit mostly goes towards operating expenses, including this website, shipping supplies and other overhead costs, and development of our next project!

1 Most Agilent, Fluke, and hp digital bench multimeters (either true RMS or average responding) as well as analog AC voltmeters such as the hp 400 series easily cover this range. Suitable analog or digital voltmeters dating from about 1967 to 2007 are widely available new and surplus at prices ranging from $5 to $150 for an older tube or transistor analog meter typically needing some restoration, $50 to $250 for a Fluke or hp 4 1/2 to 6 1/2 digit digital bench meter from the 1980's, $400 to $800 for a used 6 1/2 digit hp or Agilent 34401A from the 1990s, to $1,300 for a new Agilent 34410A. Some hand held analog and digital multimeters may not have an ACV scale sensitive down to 1 mV AC.

2 The two 9V batteries are not included because they are relatively heavy and might come loose during shipping causing damage to other parts.

Note: the correction factor from average responding to rms for noise is 1.13. The "2" superscript in the article is a reference to the Horowitz text footnote, not "squared".

JCan PCB Layout: Top pdf, Bot pdf, all layers pdf, all three zip

All prices are subject to change without notice, all sales are subject to availability of parts and kits which are in limited supply.


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