Project Solutions (2011/08/21)
Index
Remote Thermometer for the PC: PC data logger with email alerting 3
Published:2011/8/21 22:12:00 Author:Amy
Cyril Jouanjan Viewing the results After you have entered the address and name of the sensor and activated the acquisition, click OK and you will return to the main window (Figure 4). This window is updated at the same rate as the acquisition period entered earlier. If the sensor has been detected, the corresponding name is shown on a flashing green background, with the temperature ... (View)
View full text | Comments | Reading(470)
RF Detection
Published:2011/8/21 22:01:00 Author:Li xiao na
By David Daamen WiFi detectors are small gadgets that claim to detect wireless access points for computer networks. The effectiveness of these devices is already covered in many Internet articles, but here you will find out exactly how they work. To begin with, we opened the first device we had to hand; see Figure 1 (Kensington ’WiFi Finder’). It was immediately app... (View)
View full text | Comments | Reading(1003)
Remote Thermometer for the PC: PC data logger with email alerting 2
Published:2011/8/21 22:00:00 Author:Amy
Cyril Jouanjan Sensor connections The sensor used here, the DS1621, already contains practically all the necessary components. The IC also contains a built-in thermostat, but that functionality is not used in this project. The accuracy of the DS1621 is of the order of 0.5°C without the need for any special calibration. The measuring range spans from -55°C to +125°C and the... (View)
View full text | Comments | Reading(1284)
Remote Thermometer for the PC: PC data logger with email alerting 1
Published:2011/8/21 21:47:00 Author:Amy
Cyril Jouanjan With the aid of a PC and intelligent temperature sensors it is very easy and quick to assemble a professional temperature data-logger. Using e-mail, up to four temperatures can be monitored from a distance. The sensors are simply connected to the PC parallel port. In this article we describe a system that measures and records tempera* lures. The heart of the system ... (View)
View full text | Comments | Reading(494)
HIGH-END POWER AMP-High-class watts （6）
Published:2011/8/21 21:46:00 Author:Phyllis
By Ton Giesbets Don’t solder the driver transistors, output transistors or quiescent-current transistor to the circuit board just yet. The leads of these transistors must first bent to the right spacing, so they can rest properly on the heat sink without any mechanical strain after being fitted. That is described in detail under ’Final assembly’. Next comes the (View)
View full text | Comments | Reading(1425)
LED Bedside Lamp: with turn-off delay
Published:2011/8/21 21:36:00 Author:Li xiao na
By Eduard Heger If you are not lucky enough to have access to expensive test gear then lamp circuits using LEDs offer a good chance of success and allow a little bit of electronic experimentation. simple but useful addition to the bedside table. The lamp is activated either by pressing a push button or automatically when the... (View)
View full text | Comments | Reading(1595)
HIGH-END POWER AMP-High-class watts （5）
Published:2011/8/21 21:29:00 Author:Phyllis
By Ton Giesbets Power supply A separate printed circuit board has been designed for the power supply (Figure 4). It just fits into the enclosure between the transformers. The power supply design is quite conventional, with a standard 80-VA toroidal transformer, rectifier, and electrolytic smoothing (View)
View full text | Comments | Reading(3156)
HIGH-END POWER AMP-High-class watts （4）
Published:2011/8/21 21:11:00 Author:Phyllis
By Ton Giesbets IC1 is a fast dual opamp (type AD827). Here ICla is configured as a difference amplifier that compares the two signals at its inputs. R8 and R9 attenuate the loudspeaker signal by a factor of two (10.5÷2). This means that IClb only has to provide a gain of 3.5 (10.5 ÷ 2 ÷ 1.5). The gain of ICla can be adjusted using PI to compensate for variations in component values. In the... (View)
View full text | Comments | Reading(499)
HIGH-END POWER AMP-High-class watts （3）
Published:2011/8/21 21:02:00 Author:Phyllis
By Ton Giesbets To protect the loudspeakers against output offset voltage transients that may occur when the mains voltage is switched on, a switch-on delay is provided for the output relay. The delay time is approximately 6-7 seconds. The state of the relay depends on the supply voltage for the final amplifier, rather than the (View)
View full text | Comments | Reading(1330)
Marconi TF1152 RF Wattmeter
Published:2011/8/21 20:46:00 Author:Li xiao na
By Jan Builing In line with this month’s locus on all things Wireless I am coveting a vintage instrument that has given me many years of excellent service and peace of mind at o very small investment indeed. If you like to work with (View)
View full text | Comments | Reading(3027)
Frequency Spectrum from DC to 30 GHz in 4 pages 4
Published:2011/8/21 20:44:00 Author:Amy
Paul Goossens Galileo A number of European countries are collaborating on a project to create a network similar lo GPS. Just like GPS this network makes it possible lo determine your position very accurately. This new system, christened Galileo, also uses a network of satellites in space. It is anticipated that this system will be even more accurate than the current GPSI. <... (View)
View full text | Comments | Reading(408)
HIGH-END POWER AMP-High-class watts （2）
Published:2011/8/21 20:43:00 Author:Phyllis
By Ton Giesbets As can clearly be seen, all of the operating points in the amplifier are directly dependent on these two current sources, so we gave particular attention to their design. The reference voltages for the current sources are provided by flat LEDs, which in turn are operated at reasonably constant currents provided by a ... (View)
View full text | Comments | Reading(469)
HIGH-END POWER AMP-High-class watts （1）
Published:2011/8/21 20:38:00 Author:Phyllis
By Ton Giesbets The High-End Preamp preamplifier published in the April & May 2004 issues naturally calls for a matching final amplifier in an identical housing. Due to the restricted size of the enclosure, the output power of this final amplifier is somewhat on the modest side, but the quality is outstanding... (View)
View full text | Comments | Reading(6923)
＇Edwin＇ Audio Amplifier （1975）
Published:2011/8/21 20:17:00 Author:Phyllis
By Jan Buiting Blending in beautifully with this month’s focus on all things Audio I’d like to take you back to September 1975 when Eleklor magazine published an audio amplifier named ’Edwin’. 1975 was the first full year the English-language version of Elektor was published. Not surprisingly, the then editors looked at designs that had already proved extremely popular in the German and Dut... (View)
View full text | Comments | Reading(6050)