First look at JQ6500 modules

For some time, on different chinese webstores (for example Banggood) there is a module called JQ6500 for sale:

jq6500-001 jq6500-002

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 datasheet for 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:




WGX iBeacons

In a recent tutorial I explained how to detect the presence of an iBeacon with the esp32 chip. The iBeacon used to demonstrate the program is manufactured by a chinese Company, Wellcore, and sold by Banggood.

The transmitter is enclosed in a plastic, non waterproof, case of 4x4cm size:

wgx-001 wgx-002

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:

wgx-003 wgx-004

Unlike Bangood says, this iBeacon is based on the Nordic nRF51822 chip:


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:


Capacitor plague? Inside an HP 8620C sweep oscillator and HP 86245A RF plugin


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.

More details on his blog here.

Check out the video after the break.

Teardown of an HP 8671A microwave frequency synthesizer


Kerry Wong did a teardown of an HP 8671A microwave frequency synthesizer:

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.

More details on his blog here.

Check out the video after the break.

Inside a PM1A color analyzer


Kerry Wong did a teardown of a PM1A color analyzer:

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.

See the full post on his blog.

Check out the video after the break.

Teardown of a 65W Cree LED bulb


Kerry Wong did a teardown of a 65W Cree LED bulb:

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.

See the full post on his blog.

Check out the video after the break.

Sense energy monitor teardown – sampling in MHz

Sense Energy monitor teardown

Tisham Dhar did a teardown of a Sense Energy monitor:

Recently I obtained a Sense Energy monitor via US from Margaret of BitKnitting. She is doing a very interesting neighbourhood energy efficiency project. As usual I could not contain my curiosity and opened it up to have a look. I will start off with an analogy – the closest bit of open-source kit that I have to do half the amount of analog functions as the Sense is the PRUDAQ on the BeagleBone wifi

More details on his blog.

Teardown of an ATVR-1000D AC voltage regulator


Kerry Wong did a teardown of an ATVR-1000D automatic AC voltage regulator and discussed how different types of AC regulators work:

The ATVR-1000D utilizes a motor to drive the wiper of a autotransformer (Variac), the servo motor can be driven in either direction depending on the output from the OpAmp (LM324) based comparator. Comparing to a voltage regulator that uses relays for tap-switching, this type of servo-driven voltage regulator has several advantages. It offers continuous voltage adjustments as opposed to the limited discrete steps offered by relay-switching regulators. Also the output waveform is continuous.

See the full post on his blog.

Check out the video after the break.