How to measure range using frequency? Of course, You need a device called ultrasonic range meter. In this project it uses the ultrasonic frequency of about 40 KHz. The range measurement based on the time which the ultrasonic returns from the measurement object.
In order to measure the range to an object, ultrasonic transmitter-receiver system used. Three digit 7-segment LED used to display the range of measurement. The transmitter circuit of the ultrasonic generated by using two 555 timer ICs. The ultrasonic signal which was received with the reception sensor is amplified by 1000 times (60dB) of voltage with the operational amplifier with two stages.
This ultrasonic range meter made with the double sided printed board.
Read more: http://hobby_elec.piclist.com/e_srm.htm
This power supply is very simple dual power supply. With using 3 terminals voltage regulator, it’s best and simplest choice for non-critical applications. 3 terminals term is for input, ground, and output. The 3 terminals volatage regulator here are 78xx & 79xx IC (integrated circuit) series that can provide up to 1A load current.
This voltage regulator IC series have onchip circuitry to prevent damage in over heating or excessive current conditions. If the conditions happened, the chip simply shuts down rather than blowing out. These regulators are inexpensive, easy to use, and they make it practical to design a system with many PCBs in which an unregulated power supply is brought in and regulation is done locally on each circuit board.
This Dual Linear Power Supply provides a dual polarity power supply. It can be build easily for delivering up to 1 ampere with the appropriate choice of centre tapped transformer and 3-terminal voltage regulator pairs at +/- 5V, +/- 9V, +/- 12V, and so on.
The 3-terminal pair of regulators you want: 7805 & 7905, 7809 & 7909, 7812 & 7912, 7815 & 7915or 7818 & 7918. The + and – regulators do not have to be matched: you can for example, use a +5v and -9V pair. However, the positive voltage regulator must be a 78xx regulator, and the negative voltage regulator a 79xx one. The user must choose the pair he needs for his particular application.
Read more: http://www.electronics-project-design.com/DualPowerSupply.html
This switching power supply uses discrete transistor regulator MJE2955 and 2N2905. and an op-amp CA3140T functioning as a comparator in the feedback section. It provides 12V output at maximum current 10 Ampere.
This switching power supply design is very similar to that of a linear power supply, except that L1, and D1 have been added, and U1 operates in a switching mode as a comparator with a small amount of hystersis. The switching frequency of this unit varies with the output current drawn by the load. This is an undesireable feature, which is why PWM regulators are used today.
The power supply switching frequency is constant and will produce spurs only at known discrete frequencies rather than spurs at all frequencies. The Darlington-connected pass transistor block in the schematic is there twice (in parallel) for robustness. R4 in an internal trim-pot that can set the output voltage anywhere between 5 to 15 volts.
Read more: http://michaelgellis.tripod.com/power4.html
