Decibel stepper

Decibel stepper, The stepper presented here makes use of nine positions of a 12-position rotary switch. It is, of course, possible to add the three steps. As usual, the amplification factors are arrived at by connecting a number of resistors in series in the feedback circuit. The resistors used here are for the E-96 series,[…]

Read more

Power-on delay

The power supply for this analogue circuit, which affords delays of up to 330 seconds, is taken directly from the mains. The direct voltage at the output of the bridge rectifier is held at 22 V by zenzer diode D5. Resistor R6, which enables C1 to discharge rapidly as soon as the mains is switched off, must[…]

Read more

Overload Indicator

The overload indicator consists of a window comparator that measures the magnitude of an a.f signal. Two of the opamps contained in a TL072 is supplied with a reference voltage by potential divider R1-R2-R3-P1. The outputs of the opamps drive T1 via diodes D1 and D2 (that function as the half-waved rectifier), which in turn actuates D3.[…]

Read more
Fuse monitor

Fuse monitor

When an appliance ceases to —K operate, there may be various causes for this, one of which is the blowing of the mains fuse. The monitor proposed here contains an LED that lights when that is the case. It is suitable for use with fuses rated from milliamperes to amperes. As long as the fuse[…]

Read more
Burr-Brown

REF200 from Burr-Brown

Burr-Brown’s REF200 provides in independent 8-pin DIL package two independent current sources, either of which can supply 100 NA and a 1:1 current. mirror. The pinout of the device is shown in Fig. 1. Note that there are no pins for connecting a supply voltage. The correct operation of the current. sources are, however, guaranteed[…]

Read more