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Mains Frequency Monitor Circuit Diagram. Here is a simple frequency counter designed to monitor the 240VAC mains supply. It as a frequency range of 0-999Hz, so it could also be used with 400Hz equipment. Standard TTL/CMOS logic is employed for the counters and display drivers, while an ELM446 (IC1) generates accurate 1Hz pulses for gating. This device utilizes a 3.579545MHz crystal for its timebase, as commonly found in TV and video circuits and even on old PC motherboards. Mains Frequency Monitor Circuit Diagram : Mains Frequency Monitor Circuit Diagram Copyright: Silicon Chip Electronics Magazine

This Discrete Sliding Tone (Frequency Ramp) Doorbell circuit produces a low tone that will slide up to higher frequency. The equivalent total resistance connected between the base of Q1 and ground (Rbg) , and coupling capacitor  C1  determines the AF oscillator’s frequency. The resistance (Rbg) is equal to (R2+R1)R3.   Here is the schematic diagram of the circuit. The R2 is used to set the initial bias condition, adjusted to produce a pleasant low starting frequency doorbell tone. D1 will start to conduct when Capacitor C3 charge through R6 until it reaches D1 bias  voltage level.  Then the value of Rbg is paralleled by R4 and D1, and R5-D2-D3, and the values of diode’s equivalent resistance is gradually decreased as the C3 voltage ramp up.  This decreasing resistance value make the output tone slides up in frequency.  Two different diode path is provided to extend the linear area of diode conduction transition slope. With two path with different ...

This is a Simple Frequency Comparator II Circuit Diagram. The circuit provides unambiguous LED + or - bar readout with steps of 0.1%. The reference frequency is multiplied by the PLLIC1 and divider IC9 to output 64 ? F (ref) and this is then gated by dividing F (measure) by 32 in IC8 thus is F (ref) = (measure) then IC2 counts 1024 pulses. Simple Frequency Comparator II Circuit Diagram Should the count be more than 1031 than the latch IC4c/IC4a is set to indicate count too high (F (measure) F (ref)) and if the count is less than 1017 then IC3/IC4b indicate count too low (F (measure) F (ref). These signals are latched by IC5 at the end of each period by the latch signal from IC6e. When the two frequencies are within + or - 0.6% the LSB's of the counter IC2 are decoded and latched by IC7 and displayed on LED's IC6c resets the counter after latching the data.      Sourced By: Circuitsstream

Build a Voltage-To-Frequency Converter Circuit Diagram 2 . Using a Burr-Brown VFC 32 IC, this voltage-to-frequency converter uses few components. The circuit values are shown in the figure. This charge-balanced V/F converter uses a VFC32 or a VFC320 IC.  The positive charge from the 1-mA balances the negative charge from the input. V/F converter waveforms are shown in Fig. 100-l(b).  Voltage-To-Frequency Converter Circuit Diagram 2