Ordinary bipolar junction transistors can sometimes be precision sensors. When you think of precision components, you usually don’t (and probably shouldn’t) think of general-purpose bipolar junction transistors. Are GP BJTs cheap and ...
The circuit is powered for years by a single 3 volt lithium battery. It sounds an alarm when the temperature exceeds a certain point. With some minor changes the circuit could also be configured for an under temperature (freeze) alarm. The circuit ...
Op amps tend to make analog design easy. Maybe sometimes too easy? Don’t get me wrong. I like operational amplifiers. Some of my best friends are op amps. They embrace such a wide range of varied capabilities, including low noise, high power, ...
Combining an accurate temperature sensor with a standard digital multimeter can make an inexpensive, accurate, and useful thermometer. A recent Design Idea, BJT is accurate sensor for absolute temperature in Kelvin and Rankine ( Ref. 1 ), was based ...
Simple math implemented in a (very) simple circuit. What’s not to like? A very cool (also warm!) property of the base-emitter junction of (most) small signal BJTs is the ΔV BE temperature-sensing effect. ΔV BE temperature ...
Circuits such as the design described here implement useful tools for a diversity of calibration and testing applications A two-wire loop current generator is a useful tool for the testing, calibration and commissioning of current-to-pressure (I/P) ...
Figure 1 shows a simple tester, based on an ATtiny202 , a piezo buzzer, and an LED, for checking circuit wiring or tracing out the tracks on a PCB: Figure 1. The Tiny Continuity Tester based on an ATtiny202. The piezo speaker is on the reverse of ...
In the first part ( Ref. 1 ) of this Design Idea, we saw how a cheap op-amp can give remarkably precise readings from an RTD. We also found that it was a false economy, owing to incurable thermal drift. This concluding part fixes that problem by ...
In process industries, field contacts from pressure, temperature, flow switches, limit switches, push buttons, etc., are read by programmable logic controllers and/or distributed control systems (PLC/DCS) through digital input modules. They are ...
For 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. In fact, my first Design Ideas (DI) submission (in 1974) was for a 555 VFC. ...