temperature recorder

2 temperature recorder This circuit, together with a certain amount of mechanical ingenuity, makes it possible to construct a relatively inexpensive piece of equipment which can be used to record a temperature curve. An ordinary radio control servo is used to operate the pen. It uses a negative temperature coefficient (NTC) resistor as the sensor. The circuitry around Ni, N2, Ti and T2 forms an oscillator whose pulse width is determined by the instantaneous value of the NTC resistor. The resultant signal is fed directly to IC2. This IC (the SN 28654) is specifically designed as a servo amplifier, which is abundantly 81561 2 clear from its specifications: — an output current of 400 mA transistors — change of direction is accomp with no external lished with a single haoom for ere are advised to obtain the data ve r from theh manufacturers or from one of sheet supply voltage the degree of input change — the "dead space" — e in the output occurs — required before a Chang is ...