After our recent post about the commercial semi-conductor tester we started a discussion about building a similar open source project. What came up is this AVR based transistor tester (machine translation) by Markus.
It’s built around an ATmega8 IC that interfaces with a standard HD44780 16×2 character LCD. The circuit that does the testing is simplicity itself. Three pairs of resistors are connected to 6 pins of the microcontroller, and each pair is connected on the other end to one of the transistor pins.
The theory of operation is also relatively simple. The microcontroller cycles through different patterns on its output pins until a recognizable pattern is read on its input pins. It supports a very large range of devices:
- NPN and PNP bipolar junction transistors.
- P and N channel, enhanced and D type mosfet transistors.
- P and N channel JFET transistors.
- Common anode and common cathode dual diodes.
- Two diodes in connected in anti-parallel or series configuration.
- Single diode.
AVR-based transitor tester - [Link]
When building AVR DDS2 signal generator there were lots of discussions about signal conditioning in analog part of device. First argument was that LM358 wasn’t the best choice for this purpose. Another one pointed to sine wave that weren’t smooth enough.
As you can see there are some dents on it. Other waveforms also are distorted especially when higher voltages are selected. This definitely asks for better analog part. Some people suggested to replace LM358 with OPA2134, but it seems to be quite expensive choice. In my opinion low noise general purpose op-amp can be great too. I’m gonna give a try to Texas Instruments TL074 low noise op-amp. It is low power, high slew rate (13V/us) IC – almost five times faster than LM358 and for same reasonable price.
Modeling of analog part for DDS3 signal generator - [Link]
A couple of weeks ago I spent some time examining a fairly complex circuit board from my old, but still functional, clock radio/CD player. I was using the probe of my handheld multimeter to measure voltages at various IC pins and circuit traces. At one point during the process I thought, “Gee, wouldn’t it be nice if I had someone here to read the voltmeter to me as I test various points? That way I could focus on my probe and not accidentally short neighboring pins.” But then I realized that I did have someone to do just that: Microsoft Sam. I present to you the NI LabVIEW talking voltmeter:
LabVIEW: The Simple Talking Voltmeter - [Link]
Pittsford, NY, USA: Saelig Company, Inc. has introduced WiPry-Combo – the worldʼs first dynamic power meter and spectrum analyzer accessory for the iPad, iPod Touch, and iPhone – offering a modern touch interface not available on PC-based instruments. WiPry-Combo turns an iOS device into an ultraportable spectrum analyzer and dynamic power meter. WiPry-Combo brings RF power measurements to a graphical interface to show RF waveforms like an oscilloscope – instead of showing voltage, RF amplitude is displayed on an iOS portable device. Actual power output can be triggered, captured, and recorded for protocol verification or for troubleshooting wireless devices. Data is collected at up to 12 MSa/s, allowing analysis and verification of the smallest protocol level on/off times. WiPry-Combo offers data logging in csv format, while screenshot results can be instantly emailed via the iOS host phone.
In its Spectrum Analyzer mode, WiPry-Combo offers a practical solution for identifying interference or open channels in the 2.4GHz ISM band, or for identifying unauthorized WiFi access points. Operating in the frequency range: 2.400 to 2.495 GHz, it measures signals from -40dBm to +20dBm with an amplitude resolution of 2.0dBm and a bandwidth resolution of 1MHz. The band sweep time is 200ms. Read the rest of this entry »
The ACS712 is a fully integrated, hall effect based, linear current sensor. It converts the current that passes through its input pins to a proportional voltage on an output pin. He connected the output pin to an analog pin of his Arduino, and made a simple logging software that reads 1000 samples.
Current sensing with the Arduino - [Link]
For the past 3 weeks I’ve been working long nights on an open source colorimeter called the ColorHug. This is hardware that measures the colors shown on the screen and creates a color profile. Existing hardware is proprietary and 100% closed, and my hardware has a GPL bootloader, GPL firmware image and GPL hardware schematics and PCBs. It’s faster than the proprietary hardware, and more importantly a lot cheaper.
Making hardware does cost money, and I can’t give the hardware away for free like I do my other software. I’m aiming to do an initial production run of 50 units, but I’m going to need some advanced orders just to make sure I don’t get stuck with a lot of stock and no buyers. I’m offering a 20% discount on each unit, on the assumption the first users will be testing the firmware and reporting problems. If you want to support a cool open source project, I’m asking £48 for each unit, plus postage and packaging. There’s a whole website http://www.hughski.com if you want to know more about the project, and there’s even an newsletter if you don’t need hardware, but want to know how we’ re getting on.
“ColorHug”… - [Link]
This is General purpose Temperature meter for measuring Temperature from -55 ºC to 150 ºC ..It is a very useful bench test equipment for testing and finding out the temperature of various devices with unknown temperature such as room temperature , cpu cabinet, etc. The meter provides very stable readings and has excellent input sensitivity thanks to LM 35 Temperature sensor from National Semiconductor , so it can even measure small temperature change.
The LM35 is three terminal temperature sensor which gives output in the form of analog voltage. LM35 linear to the whole temperature range it generate 10 mV/ºC. this analog voltage is feed to the internal 10 bit analog to digital convertor of the PIC 18F458 which convert it into temperature and then display to the NOKIA 3315/3310 LCD.
Nokia 3315 LCD Based Temperature Meter - [Link]
This is very accurate home made LC inductance/capacitance meter built with very common components which are very easy to find all around . The range of this LC Meter is extremely good at measuring very low value of capacitance and inductance.
LC Meter’s Inductance Measurement Ranges:
- 10nH – 1000nH
- 1uH – 1000uH
- 1mH – 100mH
LC Meter’s Capacitance Measurement Ranges:
- 0.1pF – 1000pF
- 1nF – 900nF
Very Accurate LC inductance / Capacitance Meter - [Link]
This is 60 MHz frequency meter / counter for measuring frequency from 10 Hz to 60 MHz with 10 Hz resolution.It is a very useful bench test equipment for testing and finding out the frequency of various devices with unknown frequency such as oscillators, radio receivers, transmitters, function generators, crystals, etc. The meter provides very stable readings and has excellent input sensitivity thanks to on board amplifier and TTL converter, so it can even measure weak signals from crystal oscillators. With the addition of prescaller it is possible to measure the frequency of 1GHz and above.
60 Mhz Frequency Meter / counter - [Link]