This DIY digital clock plus thermometer is designed by Joe Farr and is based on PIC18F25K22 microcontroller. The complete construction details of this project including circuit diagrams, PCB layouts and PIC firmware are posted in his website. He developed his firmware using Proton PIC BASIC compiler, which is available for download for free for this particular PIC microcontroller. He uses DS1302 RTC for timekeeping and DS18B20 for temperature measurement. The temperature and time are displayed on four 2″ seven segment LED displays.
Another PIC-based digital thermometer and clock - [Link]
Inspired from one of Dave Jones EEVBlog videos on dummy load, Lee has built his own programmable constant current resistive load that allows you to draw a set current from any power supply source. His design is based on Arduino Leonardo and uses the high-power BUK954R8-60E MOSFET to control the amount of current flowing through the load path.
Constant current resistive load controlled by Arduino – [Link]
herpderp shares his waveform generator:
Here is my last project, a tiny waveform generator based on my previous project and some components:
- An AD9834 (DDS chip with sinus/triangle output)
- 2 x AD5310 (10bit DAC: one for the Vpp control, another one the offset control)
- 3 x LM7171 (Fast OPA)
- 3 x LT1616 (switching regulator: +5V, +7V, -7V)
This waveform generator is directly powered by a standard 12V jack and is capable of outputting a 10Vpp signal at 1MHz (between -5V and +5V, sinus waveform, no load). Above 1MHz, the output starts fading, reaching only 9Vpp at 4MHz (maximal frequency). Frequency, amplitude and offset are digitally controlled through the smart TFT.
Three “basic” waveforms are provided: sinus and triangle, coming from the DDS chip (0.1Hz to 4MHz, 0.1Hz step), and PWM coming from the microcontroller (0.1Hz to 1MHz, variable steps).
Tiny waveform generator - [Link]
by BasinStreetDesign @ instructables.com:
I had a bunch of random inductors in some random drawers and I wanted to know what values they were. These values are quite often not obvious by looking at the device. Colour codes for old ones were not standardized and some of the coloured rings on inductors can be faded or discoloured so that its impossible to tell what they are. Others may be unmarked and any that are hand-wound are just guess work without a meter. So I decided to make an inductance and capacitance meter which would be fairly accurate and work over several decades of value from a few nano-Henries to a few milli-Henries and also from a few pico-farads to about a micro-farad (hopefully). Sounded easy – what could go wrong?
Inductance/Capacitance Meter Saga - [Link]
By Ben Coxworth @ gizmag.com:
Ever since the Fukushima nuclear reactor disaster, there has understandably been an upsurge in the sale of consumer radiation-detecting devices. Most of these gadgets are variations on the Geiger counter, in that they alert the user to the presence and level of radiation, but not the type of radiation – which is very important to know. Researchers at Oregon State University are hoping to address that situation, with the MiniSpec. Currently in development, the handheld device will additionally tell its users what type of radionuclide is creating the radiation, and whether it poses a risk.
Small, portable and cheap radiation detector is being designed for the public - [Link]
An old but interesting app note (PDF) from Microsemi on resistorless current-sensing technique. [via]
This application note introduces a simple current-sense technique that eliminates that sense resistor, resulting in system-cost reduction, PCB space saving, and power efficiency improvement. Furthermore, the new current sensing mechanism allows higher dynamic tripping current than the static one (built-in low-pass filtering) to improve current-sense noise immunity.
A simple current-sense technique eliminating a sense resistor - [Link]
Pulse oximetry is a non-invasive method for monitoring if a patient’s oxygenation is unstable and Arduino user die_Diode sent us his version of a DIY Pulsoximter developed with two Arduino:
Arduino Mega for the oximetry electronics and Arduino Uno for the graph. The electronics includes LED Driver, Photo current transformation, patient-dependent calibration LED, Active filters, Nellcor SpO2 sensor. Adafruit OLED displays Vitalparamter. Noritake VFD display GUU-100 shows the PPG. The boards are connected to the electronics with a Protoshield.
DIY Pulsoximeter developed with two Arduino - [Link]
by Henrik’s Blog @ hforsten.com:
Ionizing radiation is something that almost anyone finds exciting (or scary) and I’ve also been for long wanted to build a Geiger counter. Unfortunately Geiger tubes have usually been too expensive to seriously consider buying them just for a hobby project. But I found out that sovtube sold soviet cold war era Geiger tubes only for a couple dollars. I bought one CI-22BG tube and one CI-3BG tube for total of 16€ including shipping from Ukraine to Finland. The site itself didn’t really convince me payment via Paypal failed because of invalid seller email address and gmail warned me that order confirmation e-mail might not have come from the address it claimed. However, I got both of the tubes and they seemed to be okay.
DIY Geiger counter - [Link]
Here’s a cheap and simple Laser Power Meter LPM for small power source, based on “MarioMaster LPM meter” by Davide Gironi:
This type of meter uses a ThermoElectric Cooling module (TEC) to measure the power of a laser. The TEC will absorb the laser light, and transform the heat generated by the laser beam to an electrical signal.
An operational amplifier is used then to amplify the signal and ouput it to a volt meter.
Voltage meter will display the power in W unit of the laser beam you are testing.
The TEC takes a little amount of time to heat, so wait until your reading became stable.
This type of meter is simple and cheap to build.
It can measure laser power up to 2W, with an accurancy of +-10mW.
A cheap and simple Laser Power Meter LPM for small power source - [Link]
Here we have it – an affordable Open Source Laser RangeFinder – OSLRF-01 from www.lightware.co.za. You can order it fully assembled and working or just PCB and optics (all other components have to find by Yourself).
An Arduino Based Laser Rangefinder - [Link]