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:
A teardown of the HP 8620C and HP 86245A by Kerry Wong:
I just picked up an HP 8620C sweep oscillator with an HP 86245A 5.9 GHz to 12.4 GHz RF plugin on eBay. This time around though, the unit does not work. While it was advertised as a working unit I could not get it powered on and there was no sign of life whatsoever. So before I start troubleshooting and repairing the unit, I thought I would do a quick teardown to see what’s inside and if I could spot anything obvious that was out of the ordinary.
I recently bought an HP 8671A microwave frequency synthesizer on eBay. This synthesizer can generate signals from 2GHz to 6.2GHz with an unleveled output of more than 8dBm. It is a nice complement to my HP 8642B signal generator and Wavetek 907 signal generator. Using these generators, I can now generate signals of pretty much any frequencies under the 12GHz range. A video of this teardown is linked towards the end of this post.
As I mentioned in one of my posts a few years back, a color analyzer from the 80’s can be a treasure trove for the hobbyists. And at the very least, it is a cheap way to get yourself a photomultiplier along with the supporting circuitry to do experiments with. For instance, you can utilize the fast response time of a PMT to do accurate speed of light measurement in a lab setting like I showed in this experiment back in 2015.
I just bought another one off eBay, and this time it is a Beseler PM1A color analyzer. By the look of it, it is probably a cheaper version of the Beseler PM2L I did a teardown and reverse engineering with before.
Upon removing the glass bulb enclosure, I was a bit surprised to see that only two power LEDs were used in this Cree bulb. Typically, you would see many more lower wattage LEDs put together to achieve higher wattage ratings. The two power LEDs are wired in series. Each power LED likely consists of eight to ten LED dies inside as the forward voltage drop of these two LEDs is measured at around 70V in operation, with each dropping around 35V. There is also a reverse polarity protection diode integrated into each of these power LEDs.
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