Sensitive-rf-voltmeter
This schematic shows a peak-reading diode voltmeter driven by two stages of amplification. A 100-ILF capacitor provides a fairly large time constant, which res...
Fet-voltmeter
A2N3819 FETprovides a solid-state VOM. The 2N3819 acts as a cathode follower in a VOM. The bias offset (meter null) is obtained with R14 and R12 sets full-scal...
Ac-voltmeter
CA081 and CA3140 BiMOS op amp offer minimal loading on the circuits being measured. ...
Dc-voltmeter
This de voltmeter, with high input resistance, uses a CA3130 BiMOS op amp and measures voltages from 10 m V to 300 V. Resistors R12 and Rl4 are used individual...
High-input-resistance-dc-voltmeter
This voltmeter exploits a number of tbe CA3160 BiMOS op amp"s useful characteristics. The available voltage ranges from 10 mV to 300 V. Powered by a single 8.4...
Full-scale-four-decade-digit
This DVM circuit uses a National ADD3501 DVM chip and an LM336 reference IC to create a simple DVM with relatively few components. ...
Voltage-level-indicator
A tricolor LED, acts as the visual indicator of the voltage level. The voltage to be measured is connected to the two comparators in parallel. The first 20-KO ...
Accurate-voltage-to-frequency-converter
This linear voltage-to-frequency converter, a, achieves good linearity over 0 to -10 V. ...
Ac-line-voltage-announcer
The range of this ac-voltage monitor is 100 to 140 Vac, with a resolution of 1 V. The speech processor interprets an 8-bit binary input code from an analog-to-...
Temperature-measuring-add-on-for-dmm-digital-voltmeter
The DVM-to-temperature adapter is built around a single IC, National"s LMlO. That micropower IC contains a stable 0.2 V reference, a reference amplifier and a ...
Temperature-reporting-digital-thermometer
The ROMs or PROMs must have the correct code for converting the data from the NE5037 -used as address for the ROMs or PROMs-to the appropriate segment driver c...
Tachometer
A standard shaft encoder"s A and B ports generate square waves with the same frequency as the shaft turns. The phase of A will lead or lag that of B by 90°,...
Low-frequency-tachometer
This tachometer lets you measure heartbeats, respiratory rates, and other low-frequency events that recur at intervals of 0.33 to 40.96 seconds. The circuit se...
Continuity-tester
The continuity tester feeds a voltage through the positive probe to the circuit-under-test, while the negative probe serves as the return line. ...
Fet-probe
This FET probe has an input impedance of 10 M!J shunted by 8 pF. Eliminating the protective diodes reduces this impedance to about 4 pF. The frequency response...
Battery-powered-ground-noise-probe
Oscilloscope measurements of ground noise can be unreliable because noise can enter your circuit via the scope"s three-pronged power plug. You can avoid this p...
4-220V-test-probe
Using inexpensive components, you can fit a simple probe circuit into a pencil-sized enclosure. When both LEDs are on, the probe indicates the presence of an...
Add-on-scope-multiplexer
The operation of the unit revolves around three !Cs: a 4093 quad NAND Schmitt trigger, a 4066 quad analog switch, and a 7555 timer. When a high is fed to probe...
Eight-channel-voltage-display
This circuit turns a common oscilloscope into a versatile eight-channel display for direct voltages. The trend of each of the eight input levels is readily obs...
Scope-extender
The adapter allows four inputs to be displayed simultaoeously on a single trace scope. For low-frequency signals, less than 500Hz, the adapter is used in the c...