Faezilkree 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. TI will require a base current of 0. To calibrate the circuit an oscilloscope is desirable so that Pi may be set exactly for the zero-crossing point. This integrator, unlike that in figure a, is non- inverting, The time constants R C and K 2 C 2 should be equal. The oscillator frequency may be varied by means of PIand the best phasing effect occurs at fre- T70DI 1 quencies between 0. Since the electrical characteristics of LS TTL devices differ from those of standard TTL ICs, the relationship between the oscillator frequency and the values of R and C will also be difficult, whilst an extra resistor is required for the circuit to function satisfactorily.
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Faezilkree 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. TI will require a base current of 0. To calibrate the circuit an oscilloscope is desirable so that Pi may be set exactly for the zero-crossing point. This integrator, unlike that in figure a, is non- inverting, The time constants R C and K 2 C 2 should be equal.
The oscillator frequency may be varied by means of PIand the best phasing effect occurs at fre- T70DI 1 quencies between 0. Since the electrical characteristics of LS TTL devices differ from those of standard TTL ICs, the relationship between the oscillator frequency and the values of R and C will also be difficult, whilst an extra resistor is required for the circuit to function satisfactorily.
However, the bottom end of R4 is returned to the output of IC1and as the voltage across Cl rises so does the output volt- age and hence the charging voltage applied to ous output pulses. It is advisable to use 1 resistors, and PI and P2 should preferably by high-quality preset poten- tiometers. At voltages belo w the zener voltage the device draws very little current. Capacitor C3, which is part of the trigger circuit of Tril, is now charged rapidly by capacitor C2 via resistor R3.
However, wlektor dealing with DC or very low fre- quency AC signals the solution is not so easy, and it is in these cases that this little gimmick will prove useful. When the input of N1 is taken low by bridging the lower pair of touch contacts with a finger, the output of N1 goes low. The IC can be a general slektor op-amp such as a3 orThe compensation capacitor C2 is not required if a is used since this IC is internally compensated.
The relative values of C2, C3 and R4 determine the lowest fre- quency ekektor which the circuit will function. 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. The use eelktor a total of ten op- amps in the circuit may seem rather excessive, but as eight of these are LM quad op-amps the total package count is only four ICs.
Bosschaert Audible logic probe o Al The voltage drop across D2 reverse-biases the base-emitter junction of Tl, so that this transis- tor is turned off and the lamps are not lit. Elektor — Circuits The nomogram once again shows the frequencies obtained for various values of R and C. Since the Y attenuators and timing capacitors in an oscilloscope are usually fairly stable com- ponents most of the drift generally takes place in the X and Y amplifiers and the rest of the time- base circuitry.
Dlektor oscilloscope time- base speed should be adjusted so that the display of the four voltage levels just occupies the whole screen width. The circuit pre- sented here can measure both voltages and cur- rents. Printed circuit board and com- slektor layout for the calibrator. If the signal injector is to be used to test cir- cuits having high voltages present, especially mains e.
The out- put of the is more than sufficient to drive a small loudspeaker. The value of R5 is dependent on the supply volt- age used and should be 33 ohms for voltages elekyor 9 V and 15 V, 68 ohms for 15 V to 25 V and ohms for 25 V to 35 V.
Should the authentic poltergeist then fail to put in an ap- pearance, the ambitions ghost-hunter can ensure success by virtue of his electronic stand-in. The circuit operates as follows: The attack time of the compressor is fixed and depends on the time constant consisting of Elemtor or 90 C2, R2 and the output impedance of the circuit feeding the compressor, which should be as low as possible.
This photo shows the output pulse obtained for an Input pulse duration of 1 ms. Should the output voltage of the regulator tend to fall then the lower end of D 5 will fall below 0 V and transistor T3 will draw more current. The direct and phase-shifted signals are summed by IC2d. This invariably means resistor values in excess of I MO, which can give timing errors due to stray leakage resistance in the circuit, or large electrolytic capacitors, which again can introduce timing errors due to their leakage resistance.
The transformer voltage thus needs to be at least 7 V to give an 8. Manufacturers of electric fires have realised this fact, and attempted to entice the consumer to buy electric by fitting the front of their fires with a coal- or log effect. With modern tor oscilloscopes this should be no problem, the supply can probably be derived from one of the low-voltage flektor in the oscilloscope either- direct or via a simple zener stabilizer. Up to about plus or minus 0. With increasing temperature the resistance of the NTC decreases and the voltage across it falls, so the output of the op-amp increases.
P2 can then be used to calibrate the ammeter. Model railway lighting Generally speaking, the internal lighting for model railway carriages is powered direct from the voltage on the rails. Elektor — Circuits Figure 1 shows the complete circuit of the signal injector.
A 1 MHz crystal is used in a parallel resonant circuit and this crystal should be a 30 p parallel resonant type. In this circuit the quiescent current through II U The DC working voltage of capacitors other than electrolytics is normally assumed to be at least 60 V.
To this end C4 and R4 are included; these components enable the preset inputs of these counters briefly when power is first applied. One of the simplest ways to achieve this electronically is to use an analogue bucket brigade shift eleltor. Related Articles.
ELEKTOR 301 PDF
How do series work? To create a series or add a work to it, go to a "work" page. The "Common Knowledge" section now includes a "Series" field. Enter the name of the series to add the book to it. Works can belong to more than one series.
Elektor Electronics 303 Circuits
Tujin The idea behind this article is not to put the pol- tergeist out of a job, but rather to provide a little 1 fun for those of our readers inclined to practical jokes. Photos, The three output waveforms pro- duced by the function generator. The signal level is increased until distortion be- comes apparent, whereupon PI is adjusted to minimise distortion. During the write-phase there will in gen- eral also be an unwanted output signal; it may be desirable to also arrange to suppress the out- put when U is low. One of the outputs is selected and fed back to the reset input of the IC, The result is a divider stage that can be set flektor any division ratio between 2 and 9.