Circuits & Schematics: frequency meter - 2

11. Ignoring the regulator's reference redux
    Christopher Paul
    Circuits Analogue Design Supply Texas Instruments OPA2383 REF35 SN74AC04 TLV9151
    .. -to-V SENSE feedback becomes mostly resistive above where: In this case, that’s 1600 Hz, well below the unity gain frequency of pretty much any regulator, and so there should be no stability issues for the overall circuit. Note ...
    Jan 21, 2026

12. Tuneful track-tracing
    Nick Cornford
    Circuits Measurement Printed Circuit Boards (PCB) Microchip MCP6002
    .. about that datum, giving a bipolar range of ~ 1 octave. Here, we need unipolar operation, starting around that -20% lowest-frequency point. Therefore, 0 Ω on the input must give ~0.3 V CC to generate a ~250 Hz tone; 12 Ω, 0.5 V CC (for ...
    .. fat power traces and long, thin signal ones while probing for continuity or shorts on a PCB without needing to look at a meter. This is simpler than it initially looks, so let’s dismantle it. R1 feeds the test probes. If they are ...
    Jan 12, 2026
13. Buck boost converter using XL6019 (bifilar choke)
    Hesam Moshiri
    Circuits Supply XLSemi XL6019
    .. from 5 V to 40 V. It uses current-mode control to improve response during voltage changes and operates at a fixed switching frequency of 180 kHz. The chip integrates a powerful N-channel MOSFET that can handle up to 5 A of switching ...
    Dec 16, 2025
14. Gold-plated PWM-control of linear and switching regulators
    Christopher Paul
    Circuits Supply Microcontrollers Usage Texas Instruments OPA2376 SN74AC04
    .. and R B , and the least significant PWM, can be eliminated, and all six inverters can be paralleled. The PWMs’ minimum frequency requirements shown are important because when those are met, the subsequent filter passes a ...
    Dec 4, 2025
15. A precision, voltage-compliant current source
    Christopher Paul
    Circuits Supply Texas Instruments TLA431 TLVH431B
    .. order of impact are the magnitude of the conductance of the R 3 + R 4 resistor string, U 1 ‘s falling loop gain with frequency, and M 1 ’s large R DS and small C DS . Still, the circuit built around the 400-V V DS -capable M ...
    Nov 25, 2025
16. Circuit makes square deal
    Stephen Woodward
    Circuits Analogue Design Texas Instruments OPA2228 OPA4228
    .. classic nonlinear analog function is the squaring circuit. It’s useful in power sensing, frequency multiplication, RMS computation, and many other odd jobs around the lab bench. Figure 1. The squaring ...
    Nov 25, 2025
17. CMOS Schmitt trigger IC makes VCO
    David A. Johnson
    Circuits Oscillators Beginners Lingxing Microelectronics CD4584
    .. changing the supply voltage fed to a classic 4584 Schmitt trigger type oscillator, the oscillator frequency can be changed over a range of 50:1. A 74HCU04 inverter is used at the output of the 4584 to maintain a ...
    Nov 24, 2025
18. 85VAC-260VAC to 12V-0.5A AC-to-DC flyback converter using an RM6 ferrite core
    Hesam Moshiri
    Circuits Supply Dongke Semiconductor DK106
    .. is RM6 and DK106 is the controller chip. The inductance of the primary winding of the transformer is 2 mH and the switching frequency is 65 kHz. Output regulation is done through a Zener diode, and the controller chip does not need any ...
    .. Then put the ferrite cores in place (in the bobbin) and measure the inductance of the primary winding using an LCR meter. If you can set the measurement frequency on your LCR meter, the best frequency is 65 kHz (switching frequency ...
    Nov 17, 2025
19. My 100-MHz VFC - the hardware version
    Jim McLucas
    Circuits Measurement Texas Instruments CD74HC14 SN74LVC1G14 74LVC1G74 TLA431 TLV9162
    .. are stubborn things” (John Adams, et al). I added two 50-ohm outputs to the schematic of my published voltage-to-frequency converter (VFC) circuit [ 1 ] (Figure 1). Then, I designed a PCB, purchased the (mostly) surface-mount ...
    Nov 14, 2025
20. Stereo digital FM transmitter circuit
    Hesam Moshiri
    Circuits Microcontrollers Usage Radio KT Micro KT0803L
    .. audio content. In this project, I have introduced a compact stereo digital FM transmitter circuit that operates in the frequency range of 87 MHz to 108 MHz. The frequency can be adjusted using two tactile push-buttons, with a 0.1 ...
    Nov 6, 2025

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