My Electronics Hobby

Fixing a Mouse Double Click Problems

2008-12-23T21:00:00.012+08:00

Have you ever experience a bad optical mouse? It went double click action whenever you did a single click action? At first, I try to Google for answer but none of them help. I’ve tried every combination of settings but the problem doesn’t go away. I really suspected there must be something wrong with the circuit. After I made a conclusion that it is a mechanical related issue (maybe the switch it self), I replace the switch from an old mouse available.

Unfortunately the problem is still there. This is dangerous since you might drag a folder by accident and move it into another folder. This problem always happening to a first time touch-pad user with tapping function turned on.

So next I’m thinking it maybe related to a noise in the circuit. So without any calculation, I try to salvage a capacitor that l can find from an old circuit board and solder it parallel to the switch.

:-) Now it become “click and hold” for about 10 seconds. The capacitor value that I used to smooth the noise from the circuit is too big causing it to simulate “click and hold”. After measuring the capacitance it shows about 2µF. Too big maybe.

Next I try to find a capacitor with quite smaller capacitance value (~2nF). Maybe this will do. So I just replace it.

Walla! At last like a brand new mouse looks and feel. Good luck.

555 Timer-Based Flyback Transformer Driver

2007-05-21T21:04:00.000+08:00

My 24kV high voltage "Jacob's Ladder" from DIY flyback transformer driver using 555 timer.

Creating an electric arc

I've always wanted to create an electric arc but don't know how. Then I come across the theory that air breaks down at about 1MV/m (Mega Volts per meter) (24kV/in). That mean you need 1kV in order to get 1mm arc. So you need a higher voltage. One of the method is to use a flyback transformer that can be found from an old TV or an old CRT PC monitor. It could generate about 10 to 30 kV. Other method is to create a "tesla coil" which is quite complicated. Maybe it will become my next project.

Flyback transformer and preparation

Flybacks can be found in all types of monitors and screens that use a cathode ray tube (CRT), e.g. TV sets, computer monitors etc. It has a big red cable with a suction cup. It looks something like below.

Next, you need to identify the primary and secondary pin out. Thanks to "Lab HV-PS page" for providing an instruction on how to find the pinout. The main HV out on the secondary coil is a big red cable with a suction cup. Now we need to find the 0V pinout for the secondary coil. The trick is to use a DC power supply. This is because the flyback secondary coil resistance is much too high. There is no way you could find it with ordinary digital multimeter.

So use your own understanding on the circuit below to find the 0V pinout. Give it about 12V and your meter should show some volts when you find the 0V pinout. For me, just to be safe, try to find a datasheet of the flyback transformer or try to find the TV or old CRT PC monitor service manual/schematics diagram to find the pinout like below. Most modern flybacks include built-in HV rectifier diode(s) and/or voltage multiplier (tripler) so output without additional components will be high voltage positive or somewhat smoothed HV DC. So, make sure your polarity is correct.

Unless you have one of these multimeter, you should get the resistance reading out of it. From my FLUKE 189 multimeter you can see that it shows more than a hundred Mega Ohm. That is why ordinary meter could not measure it because of it's limit. Below I test two types of flybacks with 112 Mega Ohm and the other about 522 Mega Ohm. Again, polarity is critical to get the reading.

To find the primary coil is a much simple than the secondary coil. The primary coil resistance is about 1 ohm and again I confirm this with a TV or old CRT PC monitor service manual/schematics diagram. In my case I could only get 0.45 ohm.

Creating the flyback driver (20kHz with 90% duty cycle)

Thanks to "Jonathan Filippi" for the idea. My circuit is quite different. I try to fix up the frequency and duty cycle with help from simulation software. I use "Electronic Workbench" to simulate the circuit which can generate about 20kHz with 90% duty cycle and I come out with this. Using 555 timer to generate 20kHz with 90% duty cycle. Next I try to put it on the breadboard and test the output from it. I get about 18kHz with 85% duty cycle. Jonathan Filippi is using 2N3904 and 2N3906 but I'm using c1815 (npn) and a1015 (pnp). I found out that you can use any multipurpose transistor and I could find it on my old TV board. For the MOSFET, Jonathan Filippi is using IRF840 but I'm using IRF630. You may try to find it's equivalent and experiment with it. Just make sure it is compatible if you want to use other types of MOSFETs. Find it's data sheet and compare the characteristic for both types of components.

Before assemble it, I test this circuit with a small transformer which I can find it on the same old TV board. Since I'm getting too excited, the quick test is to connect the output to the lowest resistance coil. I test it with a limit resistor and surprise, I can get a hundred volt out of that.

Next is to plan to transfer it to the stripboard/veroboard. Here is the stripboard layout and the assembled circuit board. Make sure you mount the MOSFET to a heat sink since it going to heat up while running/powering it up. Note that I put the 150 ohm "snubber" resistor and diode near the flyback. This is to suppress ("snub") electrical transients that might damage of the circuit.

Again, I test the assembled circuit board with the same small transformer and I could get a neon to light up. This mean I'm getting about hundred volts. Neon needs about 80V or higher in order to light up.

Test it out

Now it time to test it out. Get a high power supply for this test. Don't use an expensive lab power supply for this test. It might burn or damage. For me, I'm using a 12V DC battery charger that can give about 5 Amps. You may also try a car battery if you have one.

There is an arc!. At last, I could get an arc out of it. I try to measure the initial max. length and I could get about 24mm. Thus, it is about 24kV. Remember the theory 1MV/m?.

I measure the DC operating current. It is about 5 Amps. I've blown my DC power supply fuse in the process. Maybe I need a bigger power supply :-) . At least I've got some arcs.

Good luck!

Simplest Intercom

2007-04-06T20:55:00.000+08:00

Using old phones

Using your old phones, you could create personal "micro" telephone exchange as simple as above circuit. I manage to solder the test circuit less than a minute. Than connect the phone and test it. It works. So why 39 ohm? From Epanorama Dot Net, the correct value of the resistor should be a resistor that can limit the circuit current around 30mA total loop. The method is by replacing the resistor in the circuit with a variable resistor, plug in the phones, apply power and tune the current with the variable resistor so the current flow is 30mA. After that take out the variable resistor and measure the resistance/ohm across it. Find the fixed resistor with the nearest ohm reading to it and replace it to the circuit.

Simplest Circuit

Testing In Progress

Simple Cable Tester

2007-03-25T01:23:00.000+08:00

Simple DIY Cable Continuity Tester

How to use

This simple cable tester can be used to check 2 wire cable such as coax cable, telephone cable, audio cable and etc. Power the circuit using 9V battery. Plug in the cable and push "TEST" button. The dummy resistor is connected to the end of the cable which has 75ohm resistor inside. The tester will show only 3 conditions, "SHORT", "OPEN" and "GOOD".

How it works

The method is to check resistance of the dummy resistor at the "Terminator". The idea is simple. Imagine there is a short circuit cable under testing. The wire will act as nearly zero ohm resistor thus making the voltage divider near the dummy resistor to divide the 9V into 4.5V. Calculate it your self [ ( 1k / ( 1k + 1k ) ) * 9V = 4.5V ]. 4.5V is below than the lower "Comparator" limit (Vref 4.57V). It will trigger the lower "Comparator" and make "Short" LED to light up. Now for the open circuit cable. Assuming the open circuit cable has an infinite ohm. Voltage divider near the dummy resistor will give 9V. This is more than the upper "Comparator" limit (VRef 4.8V) and will trigger make "Open" LED light up. Other than that (both lower and upper "Comparator" didn't trigger) the "GOOD" LED will light up. For the op-amp, I'm using JRC4558 dual op-amp since I have it in my stock. You may use 741 op-amp or other multi-purpose op-amp. Learn more about op-amp here

Vref tuning

Before turning on the circuit (power it up), tune the potentiometer so that it will give the correct voltage reference to the "Comparator"s.

Upper "Comparator" = 4.8V
Lower "Comparator" = 4.57V

Extra - Low battery indicator

The extra circuit supplied is to check the battery condition. Low battery voltage (below than ~6.9V) will show "RED" light up. Else will show "GREEN" LED light up. The basic, if there is a small amount of current go through the zener (reverse bias), the first transistor (left) will be turned on making the "GREEN" LED turn on. Other than that the second transistor (right) will be turned on and "RED" LED will light up.

Modification - Add in buzzer

You add in buzzer to the circuit to make it give an audible alarm. The best is to alert us whenever the cable under test is not "GOOD". So, adding a resistor, transistor and a buzzer/beeper to the last NAND (near "GOOD" LED) will do the job. Use your own creativity for this. :-).

Upgrading DivX Player Firmware

2007-02-26T00:14:00.000+08:00

Upgrading DivX Player Firmware

Planning to upgrade your DivX player using CD? Good idea but if anything happen, your player will be dead. In order to revive it, you need to re-flash it.

Refer here for more information about re-flashing your DivX player.
Upgrading a dead player - By DivXpert.

You can download some recommended softwares from their site and try it out. Now the fun part, you need a hardware interface from your computer to the player. Recommended hardware interface by DivXpert is standard Serial Data Cable for mobile phone. So I built one.

Identifying The Upgrade Port

Open up your player and find the main PCB & the upgrade port.
Most of them have 4 pins [3.3V],[TX],[RX],[GND].
Find the label for each pin under the PCB.

What You Need

I found out that the male audio input connector from the old sound card is suitable for the upgrade port. Use it if you have one.
Old mouse cable match the female connector to this type of connector.
Find a cheap mobile serial data cable/ I'm using Nokia 3210 data cable.

Install & Join It Together

Open the data cable (phone end connector)
Join it with the female mouse connector.
Plug it into the player PCB and you are ready.
Refer " Upgrading a dead player - By DivXpert. " for detail.

My Other Version of Cable

Another option is to find MAX232 chip from maxim.
Better if you have MAX3232 since this chip is using 3.3V
I'm using normal MAX232 (5V) since I don't have one.
Because of that, I need to connect the power of the MAX232 chip to the player +5V port

After that?

Please refer to " Upgrading a dead player - By DivXpert. " for the software usage on how to upgrade. They provide the latest firmware for your Player.

Good Luck

Biquad ant. for WLAN

2006-12-23T18:45:00.000+08:00

Biquad Antenna for 2.4 GHz - 802.11b/g - WiFi - WLAN

After some research, I found out that the simplest type of homemade WLAN antenna is BiQuad antenna. Many sites provide good instruction on how to assemble it.
(refer below)

I'm not going to repeat it.

My Antenna

So I start by recycling some parts that I found in my workshop and construct it.

I took about 10-20 min. for me to finished it.

The critical process is to make the element.
With proper method and dimension this thing will work.

Good Luck!!!

ATX PSU Diagnose

2006-08-03T19:35:00.000+08:00

About ATX Power Supply

ATX Power Supply converts the wall (AC) to the direct current (DC) needed by the PC. The power supply looks like a metal box with fan. Typical computer power supply generates the voltages needed by the computer motherboard accessories. [Read more...]

Before Everything

Disconnect all socket from your main board, HDD, CD/DVD drive, Floppy drive and etc so that we can isolate which part is not working.

Step 1 - Check Wall AC power

To check this, you may try to plug in any electrical appliances to the wall socket to verify that the 240V exist such as lamp, table fan or etc. If it is working, that mean the power from the wall socket is ok. You may also check the voltage with multimeter if you have one.

Step 2 - Power Socket Fuse

If you are using power socket with fuse, you may try to check this first. The method is to plug the other end to other appliances such as your printer (turn on to verify), monitor (turn on and look for LED indicator) or rice cooker (My rice cooker using the same type of socket). Same thing, if it is ok, we know up to the power cord is also ok.

Step 3 - Voltage Selector

Not all power supply have this switch. My place using 240VAC. So if it accidentally set to 110VAC the power supply maybe burn out. No more further troubleshooting. But at place with 110VAC, maybe it will not burn out when it accidentally set to 240VAC. It will in the low voltage condition and may not start I presume. Select the correct voltage according to power provider rating.

Step 4 - 5V+ Standby Voltage

From bluemax.net

The first point that have voltage upon plug in the AC power is the standby voltage.[refer figure above] 5VSB constantly provides 5V power to the connector at pin 9. Check this voltage using volt meter to make sure that 5V exist (while the AC is turn on).

Step 5 - Simulate Power On

Now is the interesting part. To turn on your ATX power supply without mother board, the way is to make contact between pin 14 and ground pin(3,5,7,13,15,16,17). Meaning you can turn it on by connecting pin 14 with the only green wire connecting to it to other ground pin that is the pin with black wire. To verify that the power supply is working, the ventilation fan should be working split second after you connect pin 14 to ground. Paper clip would be the best choice.

Step 6 - Check All Output

Now you can check all voltage output from the power supply. You need a voltmeter in order to do that.

Pin	Name	Color	Description
1	3.3V	Orange	+3.3 VDC
2	3.3V	Orange	+3.3 VDC
3	COM	Black	Ground
4	5V	Red	+5 VDC
5	COM	Black	Ground
6	5V	Red	+5 VDC
7	COM	Black	Ground
8	PWR_OK	Gray	Power Ok (+5V & +3.3V is ok)
9	5VSB	Purple	+5 VDC Standby Voltage (max 10mA)
10	12V	Yellow	+12 VDC
11	3.3V	Orange	+3.3 VDC
12	-12V	Blue	-12 VDC
13	COM	Black	Ground
14	/PS_ON	Green	Power Supply On (active low)
15	COM	Black	Ground
16	COM	Black	Ground
17	COM	Black	Ground
18	-5V	White	-5 VDC
19	5V	Red	+5 VDC
20	5V	Red	+5 VDC

From bluemax.net

Good Luck

S/PDIF - TOSLINK interface

2006-05-10T21:22:00.000+08:00

Circuit & Information on TOSLINK interface

So you want to get a high quality audio for minidisc recording but when using red and white RCA, the quality drop drastically. Here a my cheap solution for you. Actually you can find a lot of references of this type of simple project in the internet.

REF
* S/PDIF = Sony/Philips Digital Interface
* TOSLINK = ( TOSLINK Interconnect History & Basics )
* Another web offering the same information
* SPDIF at epanorama.net

Meet my version of cheap, 2 components TOSLINK @ S/PDIF. Try to find a cable with connector from old PC casing for this. (HDD led,reset switch or power button connector)

Assemble it using your own creativity. Use the pen tube for the light transmission.

Connect it to the back of your CDROM drive. Since (D, the signal should go to anode and G should go to the ground/cathode)

Test it out. you should see the light come out from the tip/tube.

Connect to your MD or other device such as power amp that support optical in.

Actually, I have one of this (USB to SPDIF converter) for my minidisc but just to share with you on how to find a supercheap solution before start buying. :-)
Even my new MSI mainboard do have built-in TOSLINK :-)

PC IrDA interface

2006-05-05T18:48:00.000+08:00

DIY IR interface

This circuit is also from www.electronics-lab.com. Since it is very hard for me to get the infrared interface (TFDU4100), I start to look in the old/damage handphones. It looks something like this.

Now, you need to remove it using the hot air blower perhaps.

Connecting to motherboard

Please refer to www.electronics-lab.com on how connect this irda module to your motherboard.

My IrDA

Infrared Transceiver Modules

Here are the pin layout and picture of the device.

Pin Description of TFDU4100

Pin Number	Function	Description	I/O	Active
1	IRED Anode	IRED anode, should be externally connected to VCC2 through a current control resistor
2	IRED Cathode	IRED cathode, internally connected to driver transistor
3	Txd	Transmit Data Input	1	High
4	Rxd	Received Data Output, open collector. No external pull–up or pull–down resistor is required (20 k. resistor internal to device). Pin is inactive during transmission.	0	Low
5	NC	Do not connect
6	VCC1/SD	Supply Voltage / Shutdown
7	SC	Sensitivity control	1	High
8	GND	Ground

Touch Switch

2006-04-26T20:58:00.000+08:00

Experiment With NAND Gate - CMOS 4011

Output goes high when touch wires bridge by finger.

Gates Oscillator

2006-04-26T20:49:00.000+08:00

Experiment With NAND Gate - CMOS 4011

(CMOS 4011 Layout)

Circuit

Try this super-simple experiment. The output frequency is about 1kHz (square wave).

Telephone FM Transmitter

2006-04-20T00:04:00.000+08:00

Descrition & Circuit

This project is taken from www.electronics-lab.com.
With some modification, I create my own version of FM Telephone bug complete with stripboard layout.
Theortically, the frequency range is from 88MHz to 94MHz but you may experiment with the coil structure to tune it

Circuit

Strip Board Layout

Parts List

Diode	IN4384	4
	LED	1
Resistor	12k	1
	1k	1
	200R	1
Capacitor	470p	1
	330p	1
	25p	1
	12p	1
Transistor	A933(PNP)	1
Coil	*See note	1

*Coil note
7 or 8 turns of 22AWG(diameter .6mm) around 9/64inch(3.6mm) drill bit. Antenna using the same wire 22AWG, 5inch long

Picture

Compact!	With antenna!
Put it online!	Get ready to tune your radio!

Lab Power Supply

2006-04-10T21:33:00.000+08:00

Description and Circuit

Make your own lab power supply complete with adjustable voltage and constant current source.
Using single IC (LM324)

Here are the circuit.

Strip Board Layout.

Part List

1 LM324 Opamp
1 Ammeter 100 µA 1k ohm
1 Voltmeter
6 IN4001
1 Zener Diode 9.1V
1 Full-Wave Bridge Rectifier
1 LED
2 NPN Transistor, 2N3055
1 NPN Transistor, BC109C
1 Transformer
2 E-Capacitor 2200µF
1 Potentiometer 5k ohm linear
1 Potentiometer 10k ohm linear
1 Resistor 500 ohm
2 Resistor 2.2k ohm
1 Resistor 560 ohm
1 Resistor 6.2k ohm
2 Resistor 68k ohm
1 Resistor 0.22 ohm
4 Resistor 4.7k ohm

My Electronics Hobby

Fixing a Mouse Double Click Problems

555 Timer-Based Flyback Transformer Driver

Creating an electric arc

Flyback transformer and preparation

Creating the flyback driver (20kHz with 90% duty cycle)

Test it out

Good luck!

Simplest Intercom

Using old phones

Simplest Circuit

Testing In Progress

Simple Cable Tester

Simple DIY Cable Continuity Tester

How to use

How it works

Vref tuning

Extra - Low battery indicator

Modification - Add in buzzer

Upgrading DivX Player Firmware

Upgrading DivX Player Firmware

Identifying The Upgrade Port

What You Need

Install & Join It Together

My Other Version of Cable

After that?

Good Luck

Biquad ant. for WLAN

Biquad Antenna for 2.4 GHz - 802.11b/g - WiFi - WLAN

My Antenna

Good Luck!!!

ATX PSU Diagnose

About ATX Power Supply

Before Everything

Step 1 - Check Wall AC power

Step 2 - Power Socket Fuse

Step 3 - Voltage Selector

Step 4 - 5V+ Standby Voltage

Step 5 - Simulate Power On

Step 6 - Check All Output

Good Luck

S/PDIF - TOSLINK interface

Circuit & Information on TOSLINK interface

PC IrDA interface

DIY IR interface

Connecting to motherboard

My IrDA

Infrared Transceiver Modules

Pin Description of TFDU4100

Touch Switch

Experiment With NAND Gate - CMOS 4011

Gates Oscillator

Experiment With NAND Gate - CMOS 4011

Circuit

Telephone FM Transmitter

Descrition & Circuit

Circuit

Strip Board Layout

Parts List

Picture

Lab Power Supply

Description and Circuit

Part List

Component Image.

LM324

2N3055

Some Pictures.