Circuits & Schematics - 9

There are several applications at home or industry for long delay timers (ON or OFF delay). Time delays on the order of seconds can be generated using 555 timer circuits, provided the timing capacitor values do not exceed the limit specified by 555 ...

Psychologists tell us that frustration increases drive. I was driven to produce the circuit in this design idea by my increasing frustration with a collection of digital thermometers, all of which claimed accuracy to within 0.1 C but the readings ...

Latching relays change their states when you apply a short voltage pulse to their coils. Because these relays require no continuous coil currents to keep their states, you can save considerable power in the driver circuit. In one type of latching ...

An excerpt from Christopher Paul’s “Parsing PWM (DAC) performance: Part 1 Mitigating errors” ( Ref. 1 ): “I was surprised to discover that when an output of a popular µP I’ve been using is configured to be a ...

In recent EDN design ideas, we’ve seen thermostat designs that meld the functions of sensor and heater into a single device: FET, BJT, or even a simple length of fine gauge copper wire. A virtue inherent in thermostat designs that use a ...

Let’s see how you can effectively double the output sink current of the plain old 555 timer. From the block diagram in Figure 1 taken from the datasheet of the ST’s TS555 low power single CMOS timer) we can see that the Discharge pin ...

A short while back, I published a design idea ( Ref. 1 ) that uses a single linear pot to control the gain of a high performance OP37 decompensated op-amp over an unusually wide ( 30 dB to +60 dB) range. Figure 1 shows the circuit. Figure 1. ...

You can use the simple sensor circuit in Figure 1 to remotely monitor the level of liquid water in a vessel such as a swimming pool. The LMC555 sensor oscillator provides an output-signal frequency that is a function of the water level. This signal ...

The 0- to 20-mA current loop is a reliable means of data communication in industrial applications. These circuits use a precision shunt in the receiver to convert the current signal into a voltage signal. Accidentally connecting the precision ...

Pulse width modulation (PWM) is a terrific basis for digital to analog conversion. Credit goes to features like simplicity and (theoretically) perfect differential and integral linearity. Unfortunately, PWM’s need for ripple filtering tends ...