Acidbourbon posted a step by step guide of his digitally controlled HIFI amp with 4 way mixer build:
The amplifier section is trivial. You just buy a TDA1554Q, bolt it to the inside of an aluminum box, solder some resistors and capacities to the pins of the IC according to the application note in the datasheet and you have a small HiFi amplifier.
Because the volume control has to be digital, I’m using digital potentiometers. Sadly there are no (affordable) logarithmic digipots available. However I found this method which employs a linear potentiometer in combination with a fixed resistor to “fake” a logarithmic potentiometer.
Digitally controlled HIFI amp with 4 way mixer - [Link]
by Claude Haridge:
Microcontroller-based products sometimes require rotary switches. As many microcontrollers have an onboard ADC, it is easy to replace the rotary switch with a low cost potentiometer, when a rotary switch is too expensive or unavailable.
Although digitizing a potentiometer setting to act like a switch requires only a few instructions, an immediate problem is that instabilities in value occur at the switching threshold between one value and the next due to electrical or mechanical noise. The solution is to introduce upper and lower hysteresis thresholds about each transition so that the potentiometer needs to move beyond a threshold before another switch state is validated. For every updated switch state, another pair of thresholds replaces the previous. In this manner, the hysteresis provides clean switching between states.
Replace a rotary switch with a potentiometer - [Link]
Nabil Tewolde build a bluetooth OBD-II adapter. He writes:
The board is basically the reference schematic for the STN1110, which converts many OBD-II physical layers into RS232. The bottom of the board has a bluetooth module from Deal Extreme. The plan is to connect a smartphone or tablet to the device and log data.
Bluetooth OBD-II Adapter - [Link]
New GSM/GPRS/GPS/GNSS modules Quectel offer also special functions, able to make your product exquisite.
Development in the field of communication modules is fast and there are still more segments for their applications. That´s why company Quectel always comes with novelties or at least with enhanced versions of existing modules. This is also the case of two novelties M95EB and UC15.
Module M95 is certainly familiar to you from several our articles like for example Even the Vodafone confirmed quality and reliability of Quectel M95 GSM module. M95 belongs to a TOP in the segment and recently we announced you an eCall support. Meanwhile, this version came to a mass production and we can easily differentiate it by the „EB“ suffix. New version M95EB also supports Dual SIM function (DSSS), what makes it extra reliable even for emergency systems and similar applications. A previous M95 as well as new M95EB are compatible and they will be on the market in parallel, that´s why company Quectel recommends to use the new version (EB) only for applications where you plan to use these new functions.The second novelty is the UC15 module (UMTS/ HSDPA), which is similar to UC15 in many respects, but it´s smaller (29x29x2.5mm) and it has only 66 pins. The main difference is that UC15 doesn´t support GPS/ GNSS and it´s also somewhat slower (upload). UC15 is cheaper than UC20 and in many applications it can represent a very interesting alternative for a very attractive price.
A comprehensive description and comparison of Quectel modules can be found in the Quectel brochure as well as in the datasheets in particular types.
With modules Quectel UC15 and M95EB you’ ll gain Dual SIM, eCall, HSDPA and other functions - [Link]
High-performance Easy-to-use Mini Power Modules for Makers. Innovative circuitry enables positive/negative supply in one module.
PNMini is a family of high performance, easy-to-use DC/DC Power Modules for DIY electronics.
PNMini can be used as positive supply or negative supply. If both positive and negative supply rail are needed, just connect two PNMini modules together. No hardware changes are required.
PNMini is available in a small PCB package that enhances thermal performance and allows for hand soldering or plugin use. It provides +3.3V/-3.3V, +5V/-5V, or +12V/-12V output directly to your circuits requiring no external components.
PNMini – Positive/Negative Power Supply Module for Makers - [Link]
A beginner’s guide to AVR programming on instructables. It cover the basic setup to light up some leds.
Beginner’s Guide – AVR Programming - [Link]
Build this homemade “one-size-fits-most” speed controller for use with your hobby projects. It’s small, it’s flexible, and it’s built with off-the-shelf components around the venerable 555 timer IC.
Dial-a-Speed Motor Controller - [Link]
This is a review of the Sanwa PC7000 Multimeter. Video has two parts, Part1 and Part2.
Review: Sanwa PC7000 Multimeter - [Link]
In this episode Shahriar repairs an Agilent 86120B Multi-Wavelength Meter. The instrument reports “E14 Data Acquisition Problem” which corresponds to a potential internal HeNe reference laser failure. After the instrument disassembly, the old HeNe laser is removed and its optical power is compared to that of a new laser. The measurements confirm that the old laser has significantly deteriorated in output light intensity. The new laser is fitted inside the unit and the error message is eliminated. The free-space optic portion of the instrument is revealed and the principle operation is reviewed. Various components of the Michelson Interferometer is examined.
To test the correct operation of the instrument, a single tone semiconductor laser is applied to the unit and the result is compared to a different wavelength meter. The concept behind the operation of a Fabry-Perot laser is also presented before the signal is applied to the wavelength meter.
Teardown, Repair and Experiments of an Agilent 86120B Multi-Wavelength Meter - [Link]
Home automation is the residential extension of building automation. It is automation of the home, housework or household activity. Home automation may include centralized control of lighting, HVAC (heating, ventilation and air conditioning), appliances, security locks of gates and doors and other systems. This provides better convenience, comfort, energy efficiency and security. Home automation for the elderly and disabled can provide better quality of life for persons who might otherwise require caregivers or institutional care. Nowadays, semiconductor companies develop IC that integrates the system as a whole. One of which is NXP Semiconductors which they develop Home automation modem IC TDA5051A.
The TDA5051A is a modem IC, specifically dedicated to ASK transmission by means of the home power supply network, at 600 baud or 1200 baud data rate. Its single chip power line modem is equipped with protection of its output power stage and AGC (Automatic Gain Control) of input signal. With simple coupling network, this power line modem is compliance with EN50065-1 power line communication standard. This power line modem circuit uses ASK (Amplitude Shift Keying) for the modulation, and operates on 5V supply.
A home automation system integrates electrical devices in a house with each other. Devices may be connected through a computer network to allow control and may allow remote access from the Internet. Through the integration of information technologies with the home environment, systems and appliances are able to communicate in an integrated manner, which results in convenience, energy efficiency, and safety benefits.
- TDA5051AT modem IC
- Schottky Diode
- 68Ω Resistor
- 2.2MΩ Resistor
- 7.3728Mhz Oscillator Clocks
- T 630mA Fuse
- General Diode (2 units)
- 2uF Capacitor
- 47 nF/X2 Capacitor (3 units)
- 470 µF Capacitor
- 100 µF Capacitor
- 1 uF Capacitor
- 10 nF Capacitor
- 5 µF Capacitor (2 units)
- 1 mH Inductor
- 47 µH Inductor (2 units)
- 1N4006 Diode
- 250 Supply Vac
- Positive Voltage Regulator
Power Line Modem for home Automation - [Link]