Star PSS-300
So I have caught the bug. Searched for replicas of air pistol used in competitions. The KSC GP100 is just too expensive for me. The solution? Go for the replica of replica! Here is the Star PSS-300 that I got.
The grip, front and rear sights, trigger etc are all adjustable. For around HKD1000, just can't beat the price.
BTW, the Maruzen APS-3 is very nice too. But again, the price is just out of reach for me... orz
The grip, front and rear sights, trigger etc are all adjustable. For around HKD1000, just can't beat the price.
BTW, the Maruzen APS-3 is very nice too. But again, the price is just out of reach for me... orz
my "sun jar"
Tried to make my own "sun jar" around a year ago. Left it on breadboard until today...
Find the schematic below. Added a switch to keep the LED off all the time... which effective makes the whole thing a solar powered battery charger...
Notes to self:
Find the schematic below. Added a switch to keep the LED off all the time... which effective makes the whole thing a solar powered battery charger...
Notes to self:
- The solar panel is directly connected to the battery for charging. Without any control on voltage or current. May damage the battery in a long run. But then, the solar panel used is not that powerful... so....
- A normal LED requires more than 1 AA cell to power it up. To overcome this, the center-taped-coil and one of the transistor formed a switching circuit. It generates voltage high enough to light up the LED with less than one volt.
- Unlike the commercially available Sun Jar, this circuit doesn't use photoresistor to control when to light up the LED. Instead, a transistor is used to detect the voltage output of the solar panel.
Arduino test: voltmeter
First experiment with Arduino. Trying to implement a voltmeter.
Each analog input of Arduino has 1024 steps. From 0 to 5 volt. This experiment used a simple voltage divider to measure roughly 0 to 12 volt (using 50k as R1 and 4k3 as R2).
By varying the values of R1 and R2, the precision and range of the measurement can be changed.
Here is the Arduino code:
Each analog input of Arduino has 1024 steps. From 0 to 5 volt. This experiment used a simple voltage divider to measure roughly 0 to 12 volt (using 50k as R1 and 4k3 as R2).
By varying the values of R1 and R2, the precision and range of the measurement can be changed.
Here is the Arduino code:
// variables for input pin and control LED
int analogInput = 1;
int LEDpin = 13;
int prev = LOW;
int refresh = 1000;
float vout = 0.0;
float vin = 0.0;
float R1 = 50000.0; // !! resistance of R1 !!
float R2 = 4300.0; // !! resistance of R2 !!
// variable to store the value
int value = 0;
void setup(){
// declaration of pin modes
pinMode(analogInput, INPUT);
pinMode(LEDpin, OUTPUT);
// begin sending over serial port
Serial.begin(9600);
}
void loop(){
// read the value on analog input
value = analogRead(analogInput);
//Serial.print("value=");
//Serial.println(value);
if (value >= 1023) {
Serial.println("MAX!!");
delay(refresh);
return;
}
else if (value <= 0) {
Serial.println("MIN!!");
delay(refresh);
return;
}
// blink the LED
if (prev == LOW) {
prev = HIGH;
} else {
prev = LOW;
}
digitalWrite(LEDpin, prev);
// print result over the serial port
vout = (value * 5.0) / 1024.0;
vin = vout / (R2/(R1+R2));
//Serial.print("vout=");
//Serial.println(vout);
Serial.print(vin);
Serial.println(" volt");
// sleep...
delay(refresh);
}
Sun jar 2
A follow-up with the Sun Jar. After I got the jar, i noticed that there are 2 potential improvements: (1) I like it to be brighter; and (2) it doesn't last long enough (only around 5 hours even when fully charged. I prefer it to last the whole night).
Finally have time to disassemble it today and found that the rechargeable battery is only of 700mAh... -.-... no wonder... Replaced it with a 2700mAh battery... will see how it go. But of course, the question is whether the charging circuit efficient enough to fully charge the 2700mAh during the daytime.
(The circuit on the right is my experimental trial on a different approach to test if it can get a better result... both the light intensity and number of hours it can last)
Finally have time to disassemble it today and found that the rechargeable battery is only of 700mAh... -.-... no wonder... Replaced it with a 2700mAh battery... will see how it go. But of course, the question is whether the charging circuit efficient enough to fully charge the 2700mAh during the daytime.
(The circuit on the right is my experimental trial on a different approach to test if it can get a better result... both the light intensity and number of hours it can last)
太陽能電筒？
係太陽能燈先真。日間吸收太陽光為電池差電，夜間就著燈發光。
太陽能燈本身冇咩特別，但係佢又好有創意咁張盞燈放係一個半透明 jar 入面…出黎效果就好似捉左d瑩火蟲入去咁…好正！
之前係某網上商店見過有得賣，不過好貴（幾十蚊成本，但係賣成幾百蚊！）想 DIY，不過又懶。早兩日經某網友提起，今日經過某店時終於忍唔住要敗家… orz
iPod mini mod
The microdrive in my first generation iPod mini finally died a few days ago.
The 1st gen iPod mini utilizes the same Wolfson Microelectronics WM8731L audio chipset as the 3rd gen iPod (which is believed to be the iPod with the best sound quality). The technical details can be found here.
Anyway, many people has tried to mod the 1st gen iPod mini to use flash based card. Now I have a good excuse to try it :P
First thing to do is to find the right compactflash card. The key word to look for here is "ATA compatibility". The speed of the card doesn't matter. The one that I used is from the A-Data Speedy series. Picked up the 16GB model for HKD520.
The rest is easy. Just follow the online tutorial to disassemble the iPod mini and replace the microdrive.
Finally, connect the iPod mini to a computer and use iTunes to restore the firmware. Restart. And iPod mini recognizes the card without any problem.
To do: replace the battery with a higher capacity one and reinstall the Rockbox firmware later to play FLAC.
The 1st gen iPod mini utilizes the same Wolfson Microelectronics WM8731L audio chipset as the 3rd gen iPod (which is believed to be the iPod with the best sound quality). The technical details can be found here.
Anyway, many people has tried to mod the 1st gen iPod mini to use flash based card. Now I have a good excuse to try it :P
First thing to do is to find the right compactflash card. The key word to look for here is "ATA compatibility". The speed of the card doesn't matter. The one that I used is from the A-Data Speedy series. Picked up the 16GB model for HKD520.
The rest is easy. Just follow the online tutorial to disassemble the iPod mini and replace the microdrive.
Finally, connect the iPod mini to a computer and use iTunes to restore the firmware. Restart. And iPod mini recognizes the card without any problem.
To do: replace the battery with a higher capacity one and reinstall the Rockbox firmware later to play FLAC.
PIMETA headamp
After reading my DAC post, some friends asked me what exactly is my "PIMETA headamp".
The PIMETA headamp is the box on the left.
Well, first of all, headamp is an amplifier for headphones. It takes the audio signal from the source, amplify it (can be both in terms of voltage and current), and drive the headphone.
This particular headamp that appeared with the DAC is a PIMETA that I built a few years ago. It is simple to built and tune.
Here is a peek inside.
The big blue box is an Alps volume control. The four red cylinders are Elna Cerafine capacitors. The little board on the side with yellow sockets is my DIY voltage regulator to provide clean power to the headamp.
A closer look.
I fitted this headamp with 6 x BUF634. BUF634s are buffers that provide enough current to drive the headphone. They also help to drive the headamp "deeper" into Class-A.
3 x AD843 op-amps provide the voltage amplification. Different op-amps have different sound signature. Op-amp swapping is the easiest way to tune and modify this headamp.
Close up on the op-amps. These 2 are for the left and right channels. The other OPA843 is on another socket for the ground channel.
The PIMETA headamp is the box on the left.
Well, first of all, headamp is an amplifier for headphones. It takes the audio signal from the source, amplify it (can be both in terms of voltage and current), and drive the headphone.
This particular headamp that appeared with the DAC is a PIMETA that I built a few years ago. It is simple to built and tune.
Here is a peek inside.
The big blue box is an Alps volume control. The four red cylinders are Elna Cerafine capacitors. The little board on the side with yellow sockets is my DIY voltage regulator to provide clean power to the headamp.
A closer look.
I fitted this headamp with 6 x BUF634. BUF634s are buffers that provide enough current to drive the headphone. They also help to drive the headamp "deeper" into Class-A.
3 x AD843 op-amps provide the voltage amplification. Different op-amps have different sound signature. Op-amp swapping is the easiest way to tune and modify this headamp.
Close up on the op-amps. These 2 are for the left and right channels. The other OPA843 is on another socket for the ground channel.
DAC
Finally bite the bullet and got myself a DAC. Well, an USB DAC to be exact. (Anyway, my main concern is on the DAC part. The USB sound card in it is just a bonus :P)
It is the Mini USB DAC by HiFIidiy.net. Granted, it is not the best DAC out there. But given its price (< HKD900), it is tough to beat in its own class.
This DAC is based on the Texas Instrument PCM1793. And rumor said that the headphone amplifier part is a clone of the Solo.
But to my ears, my DIY PIMETA sounds much better that the built-in headamp.
On the left is my DIY PIMETA headphone amplifier, with Analog Devices AD843 op-amps installed. (If you love pop/vocal and is not a bass-head, I strongly recommend the AD843 op-amp. It might not has the details of the OPA627 / OPA637, but the tone produced by AD843 beats them all (even the OPA2111 that I have can't beat the AD843).
My current setup is: Pioneer DV-636D -> (S/PDIF) -> DAC -> PIMETA. The S/PDIF cable is a Canare cable. There were debates on the net that whether a RCA cable can really make a real 75 ohm coxial cable. But nevertheless, this Canare cable with the designed plugs seems to be doing fine... at least to my ears (These Canare plugs require a special crimp to assemble the cable... so I bought this interconnect directly from a studio shop).
The analog RCA interconnects are DIY ones made from Swiss Gotham GAC-1 cable with Canare plugs.
It is the Mini USB DAC by HiFIidiy.net. Granted, it is not the best DAC out there. But given its price (< HKD900), it is tough to beat in its own class.
This DAC is based on the Texas Instrument PCM1793. And rumor said that the headphone amplifier part is a clone of the Solo.
But to my ears, my DIY PIMETA sounds much better that the built-in headamp.
On the left is my DIY PIMETA headphone amplifier, with Analog Devices AD843 op-amps installed. (If you love pop/vocal and is not a bass-head, I strongly recommend the AD843 op-amp. It might not has the details of the OPA627 / OPA637, but the tone produced by AD843 beats them all (even the OPA2111 that I have can't beat the AD843).
My current setup is: Pioneer DV-636D -> (S/PDIF) -> DAC -> PIMETA. The S/PDIF cable is a Canare cable. There were debates on the net that whether a RCA cable can really make a real 75 ohm coxial cable. But nevertheless, this Canare cable with the designed plugs seems to be doing fine... at least to my ears (These Canare plugs require a special crimp to assemble the cable... so I bought this interconnect directly from a studio shop).
The analog RCA interconnects are DIY ones made from Swiss Gotham GAC-1 cable with Canare plugs.
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