Savel brain dump in English!

Today I decided to break apart few bluetooth headsets. I have 3 models, all made by Logitech. Most of the headsets have same, typical damage- the mic wire is broken. The problem is even described in manufacturer’s webpage. Just if you turn microphone around the headset and use some force, it breaks very small stopper and turns around. And small wire from main PCB to mic is broken.

I tested the devices with my old Nokia phone and computer using microsoft usb bluetooth adapter from mouse and keyboard. Computer detects Logitech headset, but didn’t install the “audio device”. In Logitech pages the problem is described like: “normally all devices are installed automatically”. And not a single word about “abnormal” situation. I think it is microsoft fault- microsoft bluetooth stack is lacking some “standard” elements. You need to install Widcomm drivers.

Inside the headset is nothing interesting…

On the other side of PCB is only quite big Liion cell and contacts for charger.

Main element in the headset is CSR semiconductors chip. It is MCU, DSP, audio device, bluetooth in one chip. On the right, emphasized PCB you can see something like EMI shield, but I thing that it is only some leftover from some bigger shielding.

Other components are only for charging, LEDs management and audio amplifiers.

I have few Kenwood TK-760G-1 transceivers (two-way radios) and they all were programmed to one channel and all other features were locked. In the internet and in local newsgroup I collected various software for Kenwood programming. All I needed is programming cable. My first attempt was with MAX232 adapter borrowed from Atari SIOP cable. I managed to get “-PC-” message but nothing was working. At last, I build cable exact like in some Russian internet pages. Also I hear rumour, that for programming I must use very old and slow computer. In local trash I selected P1 running at 233MHz. I soldered the cable, connected and everything is working!

The circuit diagram for programming cable is something like this:

Big image for printing.

As always, some components were not available in my closet, so I used something looking like needed 🙂
I didn’t find (in fact, I even didn’t tried to find) original transistors needed, so I replaced them with refurbished ones from old ATX power supply: A733 and C945 pair.
I didn’t used C2 capacitor. Also, R3, R4 and R5 resistors are only near needed values.

Cable pinout. At Kenwood 8 pin connector like LAN (Ethernet) port or 6 pin: GND- 3(2), RTXD- 4(3), RRXD- 7(6). In brackets you can see pin numbers for 6 pin socket.

As I understood from the description, this adapter can be used to program other types of radios. And not only Kenwood, but Motorola and other brands. BTW, this cable is called “universal programming cable”.

Original idea, schematics from Hungary by Gyula HA7JCA.

My old linear Li-ion charger somehow blowed up. I found small hole in the chip. As my all batteries were exhausted, I need to build new charger. I voted for new technology- switching charger for Texas Instruments. I selected BQ24103 chip as it is stand alone 1 and 2 cells charger. Here is the abstract from original datasheet:

SYNCHRONOUS SWITCHMODE, LI-ION AND LI-POLYMER CHARGE-MANAGEMENT
IC WITH INTEGRATED POWER FETs (bqSWITCHERâ„¢)

Ideal For Highly Efficient Charger Designs For Single-, Two- or Three-Cell Li-Ion and Li-Polymer Battery Packs.
Integrated Synchronous Fixed-Frequency PWM Controller Operating at 1.1 MHz With 0% to 100% Duty Cycle.
Integrated Power FETs For Up To 2-A Charge Rate…

In normal words, this means- simple, small, smart and very few components.

After some time I received the chip and was very disappointed. The 21-st. century technology is not very good for hobbyist. The package of the chip is “Quad Flatpack No-Lead (QFN)” with thermal pad. Translated- fucking small lead-less chip 4.5×3.5 mm size and 20 connections. The PCB pith must be 0.23mm and the distance between center of them is only 0.5mm.

I managed to build homemade PCB using simple photo-resist coated plate and old laser printer. There is small problem with mine, single sided PCB. According datasheet I need to place up to 6 thermal vias under the belly of the chip. Yeah. At home and using single side. This cause small problem described bellow.

I prepared two PCBs at once as I didn’t believe that I’ll do it at first try. The size of the inductor is a bit big. But it is the first inductor I found in my spare box.
The chip must be soldered to PCB using hot air gun, but I don’t have one. So I soldered only the PCB and build small hill on center, thermal pad. I hope the solder melted under the chip while I was scratching around the chip with my 40/20W Weller. Only X-ray can prove it. The chip moved to side for 0.1mm, but the connections are all good (I hope) and I don’t want to re-solder it.

The circuit diagram is standard, from original datasheet:

Schematics for printing

I made these changes in circuit:
Shunt resistor is 0.22 ohm as I didn’t find 0.1 one in my scrap-box. So the max charge current is 0.7A instead of 1A.
I didn’t put the thermoresistor and around elements. I placed trimmer to set working conditions. Maybe in future I do it properly.

The PSU for charger must be from 5 to 16V. While using 15V power supply the chip is very hot due to the absence of thermal vias and proper cooling. So I am using 5V PSU when charging 1 cell battery.

All elements for this charger except the chip are second-use, salvaged from old ADSL modem, wireless router and SCSI hard disk.

When we have more than one video camera and we need to watch all images at same time we can place separate monitor for each camera. But person watching all this stuff will became mad after some time. Also, we must have lots of place for all these machinery. And it is very difficult to notice changes while moving you head from one monitor to other. So here comes the video multiplexer. Today, when everything is digital, the computer manages multiplexing of video channels. But in the end of the last century, the multiplexers were stand alone devices. In local trash I acquired 16 channel video multiplexer.

This is HiTron standalone B/W multiplexer HBX16C. I didn’t find any suitable video source when I was writing this blog entry. So you can see only blank image in the picture.

You can select any channel for 16 available. We can watch them in various combinations. Also we have freeze and zoom functions in this device. As an option it is possible to connect remote control and special video recorder. Also it is alarm when video is lost. Inside we can find lots of old school electronics. No fancy SMD and BGA. Only old DIP and big chips in PLC package.

All this stuff is placed in durable standard 19″ rack mountable solid steel box. Maybe I’ll place this device on sale in my kromelis pages.

I have old, used handheld Two-way Radio Kenwood TK-248. This is quite old, max 5W power output, 136(132?)-174MHz VHF band transceiver. The batteries are almost dead, but the radios is still working. Also I have wall-cube adapter to feed device from mains and special kenwood charger. Both stations were set to single channel and I needed to reprogram them. It is quite easy to reprogram this radio. All you need is to open this sticker marked with red arrow in the picture bellow:

Under this sticker you’ll find four holes with contacts inside. All we need is to short-connect gold contacts of the left hole (viewing from the back of the device) using pencil (simple graphite pencil) or other conductive thing and switch the radio on. We must receive “SEL” on the LCD display. If you can’t get this message, keep trying as contact pads are very small.

As soon as we get “SEL” message, we are in the programming mode. Next steps are very simple. One of the first thing to be done with unknown radio is to set it to the default mode- reset it. Just press [LAMP] and [LOW] buttons at the same time and wait for red LED to light.

Programming frequency of the channels:

Enter programming mode (SEL) as described above. Press [D/A] to enter channel programming mode. If the radio is after reset or the channel is unused you must see only dashes- the channel is closed. Press [LOW] button to toggle the open or close mode of the channel. Used channel selection encoder to set desired receive (RX) frequency. If the [LAMP] button is pressed while turning encoder the frequency changes in 1MHZ steps, without button- 5kHz. Press transmit button [PTT] to set frequency to memory and jump to next setting. Now we must select QT, quiet talk frequency for receiving. Press [PTT]. Now the red LED must be on, indicating that we are in transmit (TX) part of settings. Now set TX frequency. Press [PTT] and set QT value for transmission. Press [PTT]. Now we can program next channel of just switch of the radio. While editing the frequencies you can navigate threw the channels pressing [MONI] and turning the channel selection encoder.

Setting transceivers options:

Enter programing mode (“SEL”) and press [TA]. Now you are in dealer setting mode. Turning channel selection knob you can select option value. Pressing [PTT] jump to the next option.

List of dealers mode options:

1. Allow to work in busy channel.
2. Battery saving mode.
3. Max TX time: 30, 60, 90s and OFF.
4. TX power after power up. H-5W, L-0.5W.
5. Enable [LOW] button.
6. Enable [T/A] button (Talk around/ reverse/off).
7. Enable [MONI] button.
8. Enable keyboard tone.
9. Voice scrambler KVS-1 configuration.
10. Scrambler’s KVS code.
11. Enable quite talk QT variable mode.
12. Set scanning mode.
13. Priority channel selection time.
14. Waiting time when carrier is lost.
15. Setting buttons [MONI]+[D/A] (delete/add).
16. Scan pool.

DTMF keyboard settings and everything connected to it:

To enter this mode, press [SCAN] from “SEL” mode.

17. Number of keys to use: 12 or 16.
18. Auto-dial mode when using radio as phone.
19. Number for list number 18.
20. Pause length from carrier and first DTMF.
21. DTMF length.
22. Length of the first tone.
23. DTMF usage: 1- call dialed, 2- call enabled, 3- group call enabled, 4- group call with confirmation.
24. Local code memory.
25. Spacer tone.
26. Enable group call.
27. Auto-answer mode [LAMP]+[SCAN].
28. Auto-answer mode: 1-transmitted code from 24, 2-transmitted “call” code, 3- status code.

Setting from one radio to another can be cloned. Connect two radios via cable. Turn them on holding [LAMP]+[SCAN]. Press [MONI] on source unit, the TX LED is on. After minute data is transferred. Don’t forget to change individual unit code.

Everybody knows outdoors security cameras hanged on poles, house corners and other places. Typically it is white, gray of silver colored boxes with small windows in the front. Like these:

What is inside this box? Here is one opened, but without lenses.

Contents of the box:

A) heating element. Just small heater to heat the housing and especially the lenses and window. To remove possible fog.
B) here must be lenses. Sometimes with special iris driven by camera body and sometimes moving system to change zoom, focus or even viewing angle.
C) camera body.
D) this is 12V wire for camera body.
E) heater’s thermostat. It is set to max 25 oC temperature.

Not in this housing: the PSU for 230VAC/12VDC. Some camera bodies can use 24V or 230V AC supply.

In my case, the camera body is 12VDC, heater is 230V and PSU is ugly, made in Poland transformer. It was quite hard to place this transformer inside this housing. Also simple transformer PSU it is not very suitable in mine case. The AC power is very unstable and often is missing. So I decided to remake all system to 12VDC only. I need to change heating element and ensure, that 12VDC power supply is quite powerful. I am using switch-mode PSU with 5A max output current.

For my video surveillance project I needed special video camera to make video shots in the dark. One local company offered YOKO YK-3B41 or YK-3B43 video cameras. The body, lenses and IR emitting diodes are located in the same box. The box has IP65 class and the manager in that local company told, that it is waterproof.

Inside there is Sony CCD, 12 IR light emitting diodes. 12V external power supply is needed for this device. The diodes starts to glare only then when light situation is poor.

As digital photo camera is sensible to IR wavelength light, you can see how IR diodes glares in the dark. In fact, the diodes are a bit overloaded and you can see red light with bare eye. One interesting side effect from IR light is that you can see blood-vessels under the skin if camera is used in complete darkness and is quite near the human body. Normally vessels are invisible 🙂 .

Camera was recommended as watter proof, but maybe the particular one was defective or it was only advertising myth. I played with video camera for a while, holding it in my hand and suddenly the sharpness the video image disappeared. Short glance to the lenses solved the mystery- there was fog inside the camera body, against the lenses. Somehow, the human humidity managed to enter “waterproof” camera body. The only good thing is that the mist disappeared from it after some time.

Another bad side of this camera (and all other cameras with IR backlight near the lenses) is that all the dust floating near the lenses are reflecting IR light and whole image is full of “ghosts”.

And the last comment- this model of video device is using fixed objective lenses, so it is impossible to adjust sharpness of the image.

Conclusion: expensive toy. Usable only for general surveillance.