TSP #274 – How Heavy Is an Electron? The Experiment That Changed Physics – Scope Giveaway Results

February 8, 2026 No comments

In this episode Shahriar re-traces history and measures an important characteristics of a fundamental sub-atomic particle: the charge to mass ratio of an electron.

This experiment, first performed in 1897 by J.J. Thomson, changed physics by showing that atoms are indeed made of further sub-atomic particles through the discovery of electrons. We build a setup using a pair of Helmholtz coils, a cold-cathode vacuum tube driven by a multi-kV DC power supply & careful measurements of the beam deflection angle. The theoretical foundation of the experiment is described in details.

The measured e/m ratio is compared with the NIST established number with great agreement. The historical impact of the work of J.J Thomson & Robert Milikan (measuring the charge of an electron) are also presented.

The two winners of the giveaway are:

@nicolasblomstrand2912 (YouTube)
Robert S. (Patreon)

Each will receive a Siglent SDS1104X HD!
https://www.siglentna.com/product/sds1104x-hd/

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TSP #273 – I Bought a Bridge! World’s Most Accurate Capacitance Bridge Theory, Teardown & Experiment

January 16, 2026 No comments

In this episode Shahriar dives into the concept of a capacitance bridges. In particular, the Andeen-Hagerling AH2500A Ultra-Precision Capacitance Bridge:

https://www.andeen-hagerling.com/ah2500a.htm

The theory of operation is explained in details alongside a comparison with more traditional LCR meters. A simple replica transformer-based bridge circuit is also used to demonstrate the principle operation using a Zurich-Instruments MFIA lock-in amplifier. The teardown of the unit provides further insight into the engineering design of the instrument.

The capacitance bridge is also used to measure small shifts in a parallel plate capacitor. Furthermore, a complete set of air capacitor standard modules are calibrated & adjusted using the bridge as a standard.

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TSP #272 – I found a Chub! Fluke / Hart Scientific 1529 Chub Standards Thermometer Teardown & Repair

January 3, 2026 No comments

In this episode Shahriar take a look at a broken Chub. These instruments are able to measure PRTs, Thermistors as well as other resistive based thermometers. They can also be quipped with thermocouple reader modules.

This specific instrument has a blown fuse and draws an excessive amount of current. The first problem is a faulty 5V DC/DC converter. Although changing the IC does resolve the 5V power supply problem, it is likely that the failure has also caused excessive voltage to appear across the unit. There is no activity from the microprocessor. After replacing the processor and re-programming the EEPROM, the unit is up and running. A few experiments with various sensors and precision resistors verified the functionality of the instrument.

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TSP #271 – Rohde & Schwarz Compact 8-Channel MXO3 12-Bit Oscilloscope Review, Teardown & Experiments

December 20, 2025 No comments

In this episode Shahriar takes a close look at the all new R&S 8-Channel MXO3 series oscilloscope. Despite its size, the scope retains many of its hardware accelerated functions, such zone & frequency domain triggering as well as fast spectrum modes. You can find the scope here:

https://www.rohde-schwarz.com/products/test-and-measurement/oscilloscopes/rs-mxo-3-oscilloscope_334309.html

The review is organized as follows:

00:00 – Introductions, instrument overview, overall design, interfaces
04:39 – Detailed teardown, architecture, ADCs & chipsets
11:24 – Scope class compromise philosophy
12:16 – GUI overview, sampling rates, ease of use, menu organization
15:40 – Arbitrary waveform use, waveform capture rate caveats, histograms
18:06 – SFDR, THD, noise, dynamic range, spectrum view, isolation
24:16 – DVM application, application modes, HD mode
25:38 – Connecting several signal types for analysis
25:51 – Time domain zone triggering function, rare event capture
28:11 – Frequency domain zone triggering, event rate comparison
31:58 – Power analysis application capabilities
35:00 – Hardware accelerated math function, differential signal, mask mode
36:42 – Enabling all waveforms at once, instrument speed & responsivity
37:45 – Front panel thermal considerations
37:57 – Which scope should you buy? Concluding remarks

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TNP #56 – Variable Vacuum Capacitors Exist! Analysis & Experiments with Multi-kV Vacuum Tube Caps

December 15, 2025 No comments

In this episode Shahriar takes a look at some fascinating variable vacuum tube capacitors. These devices are mechanically adjustable to achieve a wide range of capacitance values. Despite the narrow gab between the parallel cylinder plates, they support up to 10kV operation.

The internal structure & principle operation of the capacitors are covered. A Zurich Instruments MFIA Impedance Analyzer is used to measure the capacitance values across their tuning ranges. One unit has a DC motor assembly attached to the adjustment point which allows the capacitor to be electronically adjusted. Lastly, a high-voltage DC power supply is used to demonstrate that the capacitor can easily withstand its rated 5kV operation.

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