Monochromator is one of those things that has always fascinated me. Over the years, I have done quite a few experiments (I, II, III) with an EP200Mmd monochromator and it was a lot of fun. Because monochromators are such highly specialized equipment, decent ones are hard to come by at reasonable prices second hand. So my strategy has been to scour eBay once a while and pick up bit and pieces whenever I can.
Opening the module reveals a series of microwave PCB components and several active devices. A complete analysis of the module is presented. The unit is then measured and the impact of antenna impedance and power supply voltage on the output frequency is measured. The phase noise of the output signal is also measured. Using a series of servo motors, the radiation pattern of the antenna array in both azimuth and elevation is also presented.
IRIG time code generators (not to be confused with the ones used in video and film industry) are often used for clock synchronization among various connected equipment and is commonly used in power generation and distribution industry as well as in the military. In this blog post we will take a look inside a Datum 9300 time code generator from the late 80’s. A video detailing the teardown is linked towards the end of the post.
In the mid 1980’s a company called Dallas Semiconductor was producing a wide range of small RAMs with integrated battery backup. One of the more unusual item was an early attempt at an electronic key: a user would be issued a key which could then be typically used to allow access to equipment and to keep track of usage. Not very secure by today’s standards…. but an interesting data point.
Opening it up shows that it had two major parts: a silicon die and a battery. The amount of ram on the die was very small, 256 bits!
An excellent in-depth look at theTL084 op amp by Ken Shirriff:
Some integrated circuits have very interesting dies under a microscope, like the chip below with designs that look kind of like butterflies. These patterns are special JFET input transistors that improved the chip’s performance. This chip is a Texas Instruments TL084 quad op amp and the symmetry of the four op amps is visible in the photo. (You can also see four big irregular rectangular regions; these are capacitors to stabilize the op amps.) In this article, I describe these components and the other circuitry in the chip and explain how it works. This article also includes an interactive chip explorer that shows each schematic component on the die and explains what it does.
The full teardown of the unit reveals the internal architecture of the instrument, DAC / FPGA interconnect as well as the output amplifier structure. Although the limitations of the FPGA prevents the instrument to operate at full 2.5GSa/s in arb-mode, the instrument is capable of providing complex modulation up to the full 500MHz signal bandwidth.
For some time, on different chinese webstores (for example Banggood) there is a module called JQ6500 for sale:
it’s often described as a voice sound module or as an MP3 player sound module.
Actually JQ6500 is the name of the main chip hosted on the module:
The chip is manufactured by a Chinese company named JQ. A datasheetfor the chip is also available, unfortunately only in Chinese (but Google Translate can help to understand what it contains).
On the other side of the PCB, the module houses two additional integrated circuits:
a 16Mbit flash memory (25L1606E)
a 3W audio amplifier (HXJ 8002)
When you connect the module to your computer via USB, it is detected as a CDROM drive. If you browse the content of the CD, you can find the MusicDownload.exe application that allows to upload audio files in the flash memory:
The software is in Chinese but its use is very simple: by moving to the second tab you can select the MP3 files to be uploaded. If you now move back to the initial tab, you can start the upload process clicking on the only available button. In the video at the end of this post you can see how it works…
You can control the JQ6500 chip in different ways. The easiest one is using external buttons connected to pins K1-2-3-4-5:
When you press a button, the chip plays the corresponding audio file. For example if you press the button connected to pin K1, the chip plays the audio file named 001.mp3.
The onboard amplifier (HXJ 8002) is a mono IC and its output is connected to pin SPK+ and SPK-. You can therefore connect to those pins a small speaker. If you want a stereo audio, you can instead use pins ADL_L (left channel) and ADC_R (right channel) and connect them to an external amplifier.
This module is an excellent and inexpensive solution to add audio to your projects. The use of an internal flash memory has the advantage of not requiring SD cards or other media to store your audio files; in contrast its capacity (16Mbit = 2MByte) makes it more suitable to reproduce sound effects / guide voices than to make a music player.
In the next articles I will show you how to interface the module with Arduino … meanwhile here is a video showing my first tests:
The transmitter is enclosed in a plastic, non waterproof, case of 4x4cm size:
The enclosure has a hole that allows you to hang the iBeacon on the wall or alternatively use it as a key ring.
The transmitter is based on a double-sided circuit board: one side hosts all the components, while on the other side you find the lithium battery that powers the iBeacon. The antenna is also printed directly on the PCB.
A switch allows you to turn the iBeacon on or off:
The use is very simple: just turn the iBeacon on and it continuously transmits the advertising package containing its unique UUID.
The manufacturer also offers an application to customize some parameters of the iBeacon. For iOS smartphones you can download the “Wellcore Beacon Tool” app from the App Store, while for Android the apk file of the application is available for download on this website.
The app performs a scan looking for compatible iBeacons:
Once found an iBeacon, you can change some of its parameters (in the example, its name):
The change is effective as soon as you click the Write command: