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Complete circuit of the function generator. TI will require a base current of 0.
Elektor – 301 Circuits.pdf
The attack time of the rectifier is extremely short! This astable is gated on and off by the first astable. The dock frequency is then raised and a signal fed in. However, with supply voltages greater than 10 Eleitor this should not be a problem. Adjustment procedure The adjustment procedure consists simply of ad- justing the triangle symmetry and sine purity. This produces a train of short pulses from the squarewave input signal and these are fed to an audio amplifier comprising T1 and T2.
Elektor – 301 Circuits
Cl now discharges through R4 into the output of IC 1 until its voltage falls below that on the non- inverting input, when the output of IC1 again swings positive and the cycle repeats. The Table lists frequency ranges for a few capacitor values. Since the collector resistor of T1 R6 receives its supply voltage from,C4, the amplitude of the collector signal varies in sym- Flgure 1.
For example, in the prototype it was found that the circuit was reading consistently 36 pF high due to wiring ca- pacitance. The output of the calibrator can be brought out to a socket on the front panel of the oscilloscope so that the calibration can easily be checked by inserting a probe into the socket.
The proportion of phase-shifted signal and hence the depth of phasing can be adjusted by means of P4. Setting a number n on switches SI to S3 therefore gives an output frequency of n kHz.
Finally set P3 to give the required output DC level, preferably by setting the output to 0 volts with the circuit input shorted to earth. It is so compact that it can be built into virtually any oscilloscope, making regular calibration a simple procedure. For correct offset-compensation Ri and R 2 should have the same value. Figure 2 shows a circuit for triggering the alarm after a preset time delay that can be varied be- tween one second and one minute.
As the gate voltage of the FETs must always be negative the output of this oscil- lator swings bet ween ” 2 and – 6 V. When a squarewave is fed to the dock input the circuit will count up until the counter reacheswhen the carry output will go low and clock FF1.
The complete circuit of the voltmeter uses only this 1C and a handful of other components, since the 1C will drive the LEDs directly. Assume for ihe moment that R — is connected to the positive 1 14 Figure 1. A logic probe must be capable of distinguishing between low, high and undefined logic levels. The idea behind this article is not to put the pol- tergeist out of a job, but rather to provide a little 1 innocent fun for those of our readers inclined to practical jokes.
FSK modem Voltage trend meter. Photos, The three output waveforms pro- duced by the function generator.
Elektor – Circuits : Free Download, Borrow, and Streaming : Internet Archive
With PI in its mid- position both signals have approximately the same amplitude whilst at the two elektot one signal is completely blocked whilst the other is passed continuously. The count which ICS has reached is thus proportional to the duty-cycle elektot the Q output of FF1 p elekttor is proportional to the analogue input level.
P 2 is used to adjust the gain of the linyting amplifier so that limiting just occurs with the smallest input signal, this avoiding limiting caused by extraneous noises. As a rule of thumb, a safe value is usually approximately twice” the DC supply voltage. With some microphone capsules having a higher output voltage, it may be necessary to reduce the gain of the preamp to prevent overloading.
Care should then be taken that the magnetic field of the trans- former does not affect the 031 of the oscilloscope. Since the flip-flop elekfor docked by the 1, Hz signal, the FSK signal will always consist of ‘complete’ cycles of both 1, and 2, Hz. The diaphragm of the microphone is rlektor of the electret material. A conventional IF transformer is used to determine the frequency, The alignment generator is tuned to the correct frequency by passing the output signal through a ceramic IF filter.
If a particular lamp fails, the current falls, causing the relay to drop out and the LED to turn off. A portion of the signal is fed to an envelope follower, which rectifies and filters It to produce a positive voltage that follows the amplitude en- velope of the input signal.
Secondly, the values of RI to R4 should be at least ten limes the output resistance of the cir- cuit feeding the level shifter to avoid excessive loading of the output.
Operation of the manual mono switch which allows selection of mono operation if stereo reception is too noisy, is unaffected. Car ammeter A surfeit of circuits has already been published for solid-state car battery voltage monitors. The voltage across R4 is approximately mV, so Cl charges through R2 at a current of around nA, which is times lower than could be 310 if R2 were connected direct to positive supply.
Elektor – – [PDF Document]
An ideal basis for constructional projects and a comprehensive source of ideas for anyone interested in elec- tronics. Once Cl has again reached the trigger voltage of the diac, the entire cycle repeats itself. At a certain point, as the 55 iron heats up, the output from the temperature sensor will exceed the reference voltage causing the opamp output to swing negative, turning off XL R6 introduces hysteresis to avoid relay ‘chatter’.
After a short time C3 will have charged sufficiently for the output of N4 elejtor change state and the clock frequency will increase. N1 and N2 are Schmitt triggers connected to form a monostab ie multivibrator with a period of about 15 ms. The reference voltage obtained from the op-amp output can supply currents of up to 15 mA.