AM Radio Receiver Circuit Using TDA 1072AT IC

TDA 1072AT is a special purpose integrated circuit for AM radio receiver from Philips Semiconductors. The integrated circuit is designed for mains-fed home receivers and car radios. The voltage-controlled oscillator provides signals with extremely low distortion and high spectral purity over the whole frequency range even when tuning with variable capacitance diodes. RF radiation and sensitivity to interference are minimized by an almost symmetrical design. Here is the schematic diagram of this AM radio receiver circuit:

The main features of TDA 1072AT integrated circuit are:

• Inputs are  protected against damage by static discharge
• Double balanced-mixer, gain controlled RF stage
• Gain-controlled IF stage with wide AGC range
• Separately buffered, voltage-controlled, and temperature-compensated oscillator
• Double balanced mixer
• Gain-controlled RF stage
• Separately buffered, voltage-controlled and temperature-compensated oscillator, designed for simple coils
• Gain-controlled IF stage with wide AGC range
• Internal generation of AGC voltage with possibility of second-order filtering
• Full-wave, balanced envelope detector
• Electronic standby switch.
• AF preamplifier with possibilities for simple AF filtering
• Buffered field strength indicator driver with short-circuit protection

The signal coming out from pin 9 of the TDA1072AT IC  can be used to drive a meter to indicate the signal strength. [Circuit’s schematic diagram source:  Philips Semiconductor Application Notes]