Memory enhancer

This example introduces a memory booster made with the CD4069 digital integrated circuit, which has hypnosis in addition to memory enhancement and hearing aids.
Circuit Operation Principle The memory enhancer circuit consists of a low frequency oscillator, a negative feedback amplifier and a microphone BM, a transfer switch S, a headphone jack XS, etc., as shown in Figure 9-75.

The low frequency oscillator is composed of non-gates D5 and D6 and resistor R3 and capacitor C2 inside the six-gate integrated circuit IC (Dl-D6).
The negative feedback amplifier consists of Dl-D4 and resistor R2 in the IC.
When used as a hearing aid or memory enhancer, S can be placed in the "1" position. At this time, the BM converts the picked sound signal into an electrical signal, and then sends a negative feedback amplifier through S, Cl, and R1 for high gain amplification. The amplified audio signal is restored by an external earphone.
When used as a hypnosis, place S in the "2" position. At this time, the low-frequency oscillation signal generated by the low-frequency oscillator is amplified by the negative feedback amplifier, and the sound of the "tower, tower" is sounded through the external earphone, thereby playing a hypnotic effect.
Component selection
Rl-R4 uses 1/8W carbon film resistor or metal film resistor.
Both Cl and C2 use monolithic capacitors.
IC selects CD4069 or CC4069, MCl4069 type six non-gate integrated circuits.
The BM uses an electret microphone.
GB uses 9V laminated battery.
S selects the single pole double position toggle switch.