technique_valley

The circuit uses a LTC1799 precision frequency generator from Linear Technology.  A 74HC14 hex Schmitt trigger from Texas Instruments is also used to perform several other functions.  One section is wired as a simple 7Hz square wave oscillator.

This circuit will turn on a beeper when the line voltage drops below 100 volt AC.

  EDN Design Idea   This Design Idea   offers a solution to the challenge of turning devices on or off in the past. In Figure 1, IC2 is a 555-type timer (preferably CMOS) connected as a monostable one-shot multivibrator. The pushbutton switch, S1, triggers IC2. You can replace S1 with a transistor or an optocoupler, for example. You can connect VOUT to a relay or a transistor, if needed. You might need to adjust the values of R4 and R5, depending on the output load and the characteristics of S1. The interval during which VOUT remains high is T=1.1RC2. … details here  

Circuit Ideas for Designers App Note - … more details here  

First Generation design that means it is not our latest design.  …  

Information and details regarding test setup and calibration, and how to use the evaluation software for data capture can be found in the CN-0269 Software User Guide In order for another controller to be used with the EVAL-CN0269-SDPZ evaluation board, software must be developed by a third party. . . more details here  

DN297 Design Notes (Linear Technology). . . more details here  

System Performance Figure 4 shows a plot of the ADC code occurrences for 10, 000 samples (1 sec at 1 kSPS) when CH0 through CH7 are shorted to GND on the terminal block of the evaluation board. Note that 95% of the codes fall within 4 LSBs, and the peak-to-peak spread is approximately 7 LSBs. The sampling rate 250 kSPS is controlled by the system demonstration platform ( EVAL-SDP-CB1Z ), and the digital signal processing including the signal windowing and FFT is calculated on a PC by the CN-0254 evaluation software. . .   for detail click here

DN35 Design Notes (Linear Technology). . .

A variable notch filter with both high and low pass filters.  For audio frequencies 100Hz 10KHz …

High input impedance Amplifiers are ideal for buffering high impedance networks. Here a twin-T notch filter is shown to reject 60Hz signal content by more the 60dB. Small size, low valued capacitors can be used at such a low frequency with high valued resistors when using a CMOS op Amp… 

This circuit is the audio Amp section for a complete optical transmitter.   The circuit Amplifies and filters the voice audio signals from an electret microphone.  The circuit is described in more detail in the receiver section of Dave Johnson's.

This is a collection of inverting and non-inverting active low pass filter circuits.  I included one, two three, four and six pole filter circuits.  You can change the component value ratios shown to achieve any frequency cut-off you may need . . .

This circuit uses a switched capacitor filter IC from National Semiconductor to filter signals with frequencies higher than the 3KHz needed for voice audio. The schematic includes an audio Amplifier that is designed to drive a standard audio head phone.

This file will be usful for anti-aliasing or band limiting in an audio system.   The op amp is a Linear Technology, LT1123, LT1355, or LT1169…

The filter is a simplified state variable architecture consisting of two cascaded 2nd-order sections.  Eaqch section uses a 360 degree phase shift around the two op-amp loop to creat a negative summing junction…

This is a collection of inverting and non-inverting active high pass filter circuits.  I included one, two three, four and six pole filter circuits.  You can change the component value ratios shown to achieve any frequency cut-off you may need. The circuit does not specify an operational Amplifier.  The circuits should be used to select the needed resistor and capacitor components for a particular frequency knee and  slope.

For some RFID systems operating at 125KHz, a very low distortion signal source reference is needed.  This hobby circuit shown on this page produces a 10-volt peak-to-peak signal into a 50-ohm load, with a distortion of only 0.01%.

This new loop antenna is his best design yet and I am proud to be the first to present his work. It uses one, six foot square, six turn loop, and is aperiodic in nature, covering the frequency range 50KHz, 5000KHz… [Design by Graham Maynard].   Notes.   This new loop antenna by Graham Maynard is his best design yet and I am proud to be the first to present his work. It uses one, six foot square, six turn loop, and is aperiodic in nature, covering the frequency range 50KHz - 5000KHz. The loop is of a size that can be mounted inconspicuously against a garden fence away from household interferences. This new '6x6' design uses the centre tapped loop winding as an input phase splitter. This ensures low distortion push-pull operation. The amplifier also has a low impedance shunt input which maximises gain. These aspects give it a better signal to noise ratio than with a single ended or high impedance amplifier. The amplifier provides a useful gain of 42 -

This crystal controlled circuit drives a 40KHz piezoelectric transducer with a 30v peak to peak signal.

This crystal controlled circuit drives a 40KHz piezoelectric transducer with a 30v peak to peak signal.

A X100 transistor Amplifier is followed by a zero cross detector circuit, using a voltage comparator.  The output is a TTL logic signal, corresponding to the received 40KHz signal.

A while back someone needed a simple way to generate a negative 0.5v supply from a conventional transformer type AC to DC power supply.  The circuit below uses a couple schottky diodes and a filter capacitor to perform the feat.  The circuit is handy when using “rail to rail” op Amp circuits which get close to zero volts at their output from a single DC supply but can’t quite deliver without a negative supply.  With the aid of the 0.5v supply circuit shown, those devices can produce a true zero output voltage.

This is simple way to power some 5v logic from a 240vac source.  If a 120vac power adapter is used, the circuit will also work for 120vac power lines.

This is a classic linear power supply which produces a regulated 18v, rated at about 1 Amp.