Circuits & Schematics: frequency meter

1. 5-V ovens (some assembly required). Part 2
   Nick Cornford
   Circuits Supply Microchip MCP6002
   .. similar. At least this was designed from scratch. U1a forms a conventional oscillator running at around 1 kHz. Neither the frequency nor the exact wave-shape on C1 is critical. R1 and R2 + R3 determine the tri-wave’s offset, and ...
   .. of millivolts. (The fine copper wire used to connect the module to the outside world has a resistance of about 1 Ω per meter.) Q1 drops ~1.3 V and so provides about a third of the heating, rather like the corresponding device in Part 1. ...
   Apr 7, 2026

2. 1 MHz 555 VFC
   Stephen Woodward
   Circuits Measurement Texas Instruments LMC555 TLV9051
   .. decades, I’ve had a fascination with voltage-to-frequency converters and the 555 analog timer chip, and therefore a double obsession with VFCs based on the 555. ...
   Mar 27, 2026
3. 5 decade antilogarithmic PWM current source
   Stephen Woodward
   Circuits Supply Texas Instruments LMC555 LTC2066
   .. pages of Design Ideas (DIs) have recently been awash in a veritable cascade of designs for variable frequency oscillators with frequency ranges tunable over multiple decades: Self-oscillating sawtooth generator ...
   Mar 26, 2026
4. DC to DC buck converter [Adjustable, 97% efficient, 3 A]
   Hesam Moshiri
   Circuits Supply MPS MP2315
   .. Figure 1. Schematic diagram of the DC to DC buck converter. According to the MP2315 datasheet: “The MP2315 is a high frequency synchronous rectified step-down switch-mode converter with built-in internal power MOSFETs. It offers a ...
   Mar 18, 2026
5. 3V sweeping siren alarm
   David A. Johnson
   Circuits Audio Oscillators Analog Devices LTC1799
   .. some thought and came up with a design in Figure 1. Figure 1. Schematic diagram. The circuit uses a LTC1799 precision frequency generator from Linear Technology. A 74HC14 hex Schmitt trigger from Texas Instruments is also used to ...
   Mar 17, 2026
6. 555 VCO revisited
   Uwe Schüler
   Circuits Oscillators Texas Instruments TLC555
   .. is well known that a 555 timer in astable mode can be frequency modulated by applying a control voltage (CV) to pin 5. The schematic on the top of Figure 1 shows this ...
   Mar 13, 2026
7. Simple shorts sniffer
   Stephen Woodward
   Circuits Measurement Printed Circuit Boards (PCB) Texas Instruments TLV9052
   .. loaded boards and boards with shorts in ground planes. Here’s how it works. Figure 1. Audible milli-ohmeter output frequency is linear versus resistance over several orders of magnitude. A 50-mA excitation current is provided to ...
   Feb 25, 2026
8. Self-oscillating sawtooth generator spans 5 decades of frequencies
   Christopher Paul
   Circuits Oscillators Analog Devices ADA4891-1 LM4041 LT1720
   .. oscillating circuits. Here’s a method that employs a single supply voltage rail to produce a buffered signal whose frequency can be varied over a range from 10 Hz to 1 MHz (Figure 1). Figure 1. The sawtooth output waveform is ...
   Feb 16, 2026
9. Full circle current loops: 4 mA-20 mA to 0 mA-20 mA
   Stephen Woodward
   Circuits Analogue Design Measurement Interfaces Texas Instruments TLV431
   .. that Design Idea (DI) contributor and current source circuitry expert Ashutosh Sapre discovered to be essential for frequency stability of the cascode topology. Thanks, Ashu! Figure 2. R4 and R5 trims allow post-assembly ...
   Feb 13, 2026
10. Transformerless 85-260VAC to 12VDC-0.2A power supply
    Hesam Moshiri
    Circuits Supply Diodes AL17150
    .. AL17150-10B achieves excellent regulation and high-power efficiency. The characteristics of max peak current and driving frequency vary as the load changes, which can improve efficiency performance at light load and overall average ...
    Feb 12, 2026

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