This is a joule thief circuit with a schottky diode at the output. In the video I show that it can power an LM386 based audio amplifier connected to 50-80W speaker. It has a poor regulation but can give about 130mA @ 5V
At first i tried to implement this idea using opAmps to control the position of the object and i spent few hours trying to make it work to no success. Then I though of using Arduino and the idea is simple.. variating the strength of the magnetic field according to the Analoge input of the optical sensor (you can use a hall sensor too).
The LM2576HV - 0.5 is a 5V switching regulator capable of delivering 3A.
It requires a DC input voltage between 7 and 60V to deliver a fixed 5V on the output.
In my setup (12V input) i tested it with 1.5 Ohm load and found the input current to be 1.8A and the output current 2.6A. I found it interesting because it can be used as an Efficient pre-regulator for linear regulators!
I also tried to configure it as adjustable voltage regulator (5 to 11.44 V) using the same 12V on the input but im not sure if its safe to use it this way because there is a different dedicated version of the LM2576 for use as an adjustable switching regulator.
Lately I have been working allot with inductors, ex: DC/DC converters and had a problem not knowing the inductance of most coils I worked with so I decided to build an inductance meter using Arduino and LM393 Comparator. I found the AVR LC meter with frequency measurement project by Kerry D. Wong very helpful, it made me understand the concept behind the measurement . The schematic and Arduino code based on similar project by ReiBot.org. This meter is not very accurate compared with profesional ones but it does the job.
Update: A better Arduino sketch by ultimoistante: code here.
In my previous post I showed an adjustable step-down configuration of AX3003 (SMD buck converter salvaged from old electronic equipment ) and i was wondering what would it take to turn it into a boost converter when I found this paper http://www.ti.com/lit/an/slyt286/slyt286.pdf
It shows how to use a buck converter in an inverting buck-boost topology.
Important note: The paper calls for connecting the Vss pin of the buck device to Vout but if i keep the Vss pin floating (not connected) and connect the Feedback network to Vin instead of Vout, the output voltage goes over -50V !!! (serious boost)!
SMD buck converter from AXELITE in TO252-5l package was salvaged from some old electronic equipment. Its capabel of taking up to 22V input and outputting adjustable voltage from 1.23V to 19.5V / Up to 3 Amps! It has 80% efficiency (12 to 5V (2A) ) and 75% (12 to 3.3V (2A) )See datasheet
The circuit is derived from the well known DC boost converter circuit using 2 transistors to switch the MOSFET (PNP and NPN). The RC (10nF and 1K) decides the frequency. Higher capacitance gives lower frequency and lower resistance gives higher frequency. The circuit works but im not sure if its the best way to build a DC boost converter. However its the simplest i could think of.
Using iCircuit App for iPhone (Shadi Soundation 2012)
I tried to build a flyback converter (or what i think should be called a Flyback converter) using the KHB4D5N60F MOSFET but had a problem with current draw! So i decided to use a Power Transistor E13009 then it worked fine. I used the 74HC14 PWM circuit (previous post) to switch the transistor. The converter has a couple of flaws (the 12V input comes from a 90W power Supply), .. one of them is the heat dissipation!! Although it can deliver allot of power it heats up fast (BBJ vs MOSFET stuff ... mmmm )
Input: 12V, Output: ~60V without load. About 5.5 Amps with 24V DC Motor Transistor: E13009, Diode: UF3003, Transformer from an old SMPS ,PWM with 74HC14 Important notice: Circuit is not efficient and it was built for experimental reasons only.
In my previous post i showed a modest 12v to ≈70V boost converter. I used the signal generator of my DSO Quad to switch the MOSFET and was about going the popular way of using a 555 timer chip in astable configuration to do the switching when I had the idea of using the famous astable multivibrator/oscillator circuit (pair of NPN transistors, 4 resistors, 2 capacitors).
I was concerned about the calculations of resistors and capacitors values to set the frequency and duty cycle, so i decided for 50% duty cycle which simplifies the calculation process.
Schematic using iCircuit App. for iPhone
Normally you would determine the frequency using: F = (1 / 0.693*(R2C1 + R3C2))
But in case of 50% duty cycle: F ≈ 0.721 / RC (while R2 = R3 and C1 = C2)
I did choose 10K for R and 1nF for C so I have approximately 72 KHz
The multivibrator circuit on breadboard
Important notice: everything here is experimental ..
and such a DC converter and switching method are not a suitable for application!!
This is my first boost converter (12v to ~70v) using A MOSFET (KHB4D5N60F), self-built coil, a fast Diode (B10A45VI - by the way its the wrong diode, click here to see why) and a 47uF/400v capacitor Switching Freq. is about 50KHz, 50% DUT
In video: I used a small NPN transistor to switch the MOSFET because the pulse from my handy function generator did not provide enough current to do so. Loads: 24V DC motor and 12V (20W) Halogen bulb! connected once in series and then in parallel. The converter can handle about 4A current
Schematic using iCircuit - This circuit is experimental only and not suitable for application-
Arduino and R-2R DAC working as a signal generator. Check this link for detailed info. I went a different way with the coding inorder to add a delay function between individual pulses and not cycles so i could influence the frequency. The code is big and it took sometime to write but it worth it not only for the delay but for the resolution too. Here you can download my Arduino sketch (R_2R_DAC). The DIY Arduino GLCD Oscilloscope by Filear.com.
Important note: I use the digital pins (3-10) and the sketch works only for these pins because i initialized them using DDRD and DDRB
The amplifier operates in a way similar to pulse-width modulation. The 555 modulates the Audio input with a frequency higher than the speaker response capability so the modulating frequency is dropped (the coil in the speaker acts as a HF filter) and the input signal is being played by the speaker Note1: Adding a 100n cap between pin 1 and 2 will dramatically increase the volume, distortion and heat up the chip very fast. Also (from original circuit) adding a capacitor across the speaker terminals will increase the volume and distort the output but without heating the chip. Note2: To add a volume control, replace the 100K connected between the Transistor base and ground with 100K Pot. Note3: The transistor used in this circuit is BC547, the IC is NE555 and the actual DC supply is 12V.
Monolithic power amplifier with a wide supply range (16V - 60V). It delivers 20W into 4 ohm or 8 ohm speaker. Using +/- 30v it delivers over 30W to 8 ohm speaker.
Some important Datasheet Notes:
Note 1: Twist Supply lead and supply ground very tightly. Note 2: Twist speaker lead and ground very tightly. Note 3: R1C1 band limits input signals. Note 4: All components must be spaced very closely to IC.
I did set up a Windows (IIS) web server on my old IBM ThinkPad X30 machine and using the DNS host service from no-ip.com I can access the web server over the internet using an URL instead of my dynamic IP address. no-ip.com offers a client for Windows, Mac and UNIX that checks the WAN dynamic IP address and updates the DNS service with the new dynamic IP! no-ip.com let you create multiple DNS hosts for dedicated services like Http, ftp, .. etc and using their client software i mentioned before you can choose which host (service) you want to activate and also link to the server machine or other machine on the network.
Transmitting sound using LED or a cheap laser pointer and receiving it using a photovoltaic cell and a small amplified speaker! The Audio signal modulates the power feeding the laser pointer and so it does change its brightness corresponding to the change in the amplitude of the audio signal. A solar cell converts the variations in light back to electrical signal and outputs it to the small amplified speaker !
Controlling home appliances using Twitter for Computer or for Mobile (iPhone and other internet capable mobile devices)!
Twitter message turning ON/OFF 4 different home appliances!
Arduino UNO - EthernetShield - LCD - Relay
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