Yet Another Scanning Monochromator Build

A while ago, I saw a video on the signal path in which Shahriar modified his Verity EP200Mmd monochromator/detector and turned it into a scanning monochromator. Inspired by his work, I decided to do something similar. Since I do not have the equipment to make the mechanical pieces, I decided to take another route. In this post, I will show you a simple and non-intrusive way to make the EP200Mmd a scanning monochromator. A video discussing the build and some experiments is included towards the end.
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LM2596 DC-DC Converter Module Testing

LM2596 based step-down DC-DC converter modules can be bought on eBay quite cheaply for around a dollar each. But how do they perform? Is it safe to use it to power your design? Let’s find out.
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Teardown of a Cisco CSS 11503 Content Services Switch

This old Cisco switch was on its way to the dumpster at my work place, so I thought I would rescue it. After all, while there are plenty of teardowns of consumer grade networking gear on the internet, teardowns of enterprise level network equipment have been hard to come by. So at the very least it would be a good opportunity to take a good peek inside.
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Oscilloscope Probe Rise Time Testing

In this blog post, I compared the rise time of four oscilloscope probes of various bandwidths using an avalanche pulse generator and a Tektronix 2465 300 MHz oscilloscope. The bandwidth of an oscilloscope probe is typically characterized using a network analyzer. But using a sub-nanosecond rise time pulse generator and a reasonably high bandwidth scope, we can infer the approximate bandwidth of the probe under test using the following equation:
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Wavetek 859 50 MHz Pulse Generator – Reparied

During the teardown of my Wavetek 859 pulse generator last week, I pretty much concluded that it was beyond economical repair since there definitely was something wrong with the main processor board. Well, after spending some time analyzing and troubleshooting I was able to fix it after all. Towards the end of the post I included a video showing this pulse generator in all its glories.
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Wavetek 859 50 MHz Pulse Generator Teardown

In this blog post, let us take a look at a Wavetek 859 50 Mhz pulse generator. This pulse generator was made back in the 1980’s and has long been obsolete since. I got this unit next to nothing as it was not working and I was told that multiple boards might have failed. Even though it might not be repairable, we can still learn quite a bit from a teardown. If you just wanted to watch the teardown video instead of reading through the post, you can scroll down to the bottom.
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PPS-2322 Performance Verification and Automatic Fan Controller Design

As I mentioned previously, Amrel PPS-2322 (dual 32V/2A) does not have a fan controller so the fan is on whenever the power supply is on. The fan noise can become quite annoying and distracting. So I built a simple fan controller which would turn the fan on and off automatically depending on the heatsink temperature.
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Amrel PPS-2322 Programmable Power Supply Teardown

I picked up an Amrel PPS-2322 programmable power supply from eBay recently. You probably have not heard of the Amrel brand before as American Reliance (Amrel) no longer makes power supplies nowadays. Its power supply division was acquired by AMETEK Programmable Power, a subdivision of AMETEK back in 2010. While Amrel power supplies had been discontinued, Amrel branded electronic loads are still being actively developed and sold by AMETEK.
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Guarding Explained

In electronics, guarding is a technique typically used to prevent or minimize current leakage from a high impedance source. This method is widely used in many low level measurements especially in low current and high resistance measurements.
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Building A Laser Oscilloscope

You can generate some pretty amazing patterns by shining a laser onto a mirror mounted on a vibrating speaker cone, a lot of people have experimented with this kind of laser show. But how about building a true laser oscilloscope that is capable of displaying signals? In this post, I will show you just that. For those who are impatient, I included a video towards the end.
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When to Use An Electrometer?

Electrometer is a piece of highly specialized electronic test equipment. Most of us would naturally associate it with low-level measurements (e.g. low current pA, fA and high resistance GΩ measurements) only, but the situations under which you might need to use an electrometer are actually far more common then you might have thought. In this post I will discuss a couple of situations where using an electrometer is crucial. And at the end of the post I included a video for some demonstrations.
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Samsung Galaxy S-Pen Waveform Capture

I was quite intrigued by the S-Pen that came with my Samsung Galaxy Note 4. According to the specifications listed on Samsung’s site, the S-Pen supplied with Samsung Galaxy Note 4 he S-Pen supports 11 bits (2048 levels) of pressure levels and can be detected at a 15 mm hovering distance from the phone surface.
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Keithley 614 Electrometer Teardown

In this blog post, we will take a look inside a 1980 vintage Keithley 614 Electrometer. While it was designed and built more than three decades ago, its performance is still pretty impressive (10 fA current resolution) even compared with today’s modern standards. Its performance was only rivaled by Keithley 617 in its days.
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Turn Your Android Phone into a Wireless Touchpad

In this blog post, I will show you a simple way of turning your Android phone into a wireless touchpad. For this to work all you need is your Android phone, an Arduino board and a HC-06 (or HC-05) bluetooth module based on BC417. A short demonstration video is included towards the end of the post.
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Reverse Engineering a Beseler PM2L Color Analyzer

I recently acquired an old Beseler PM2L color analyzer. This kind of color analyzer was designed to analyze the color or exposure of film negatives at a certain location by comparing the intensity of the filtered light of each color channel (CMY and white). The PM2L model was made in the 70’s through early 80’s and has long become obsolete. But since it has a 931A photomultiplier tube (PMT) inside, you can easily repurpose it for other uses. And the good news is, these old color analyzers are cheap on eBay. You can usually grab one for a price cheaper than a bare PMT itself.
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