DIY Memo: ESP8266 v12 analog I/O

This is an amendment to the previous ESP8266v7 memo. More specifically, the I/O pins don't behave exactly as described by internet sources. A little bit of background: I was presented with a challenge to read from an analog sensor and send the reading through wifi network to the cloud. This can be accomplished easily using… Continue reading DIY Memo: ESP8266 v12 analog I/O

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Memo: Phase-locked loop

Phased-lock loop (PLL) synchronizes the frequency of output and input signals. The output signal is generated internally as part of the phase-lock loop; specifically from its variable-frequency oscillator (VFO). PLL applications PLLs are primarily used for clock synchronization within IC packages, encompassing the whole or parts of the IC's (signal processing) circuitry within its loop… Continue reading Memo: Phase-locked loop

Memo: Analog multiplier and voltage-controlled circuits

Analog multipliers are commonly available as integrated circuits (IC) and are rarely constructed from scratch due to their complexity. Multipliers commonly have 8 pinouts: X1, X2, Y1, Y2, W, Z, +VCC, -VCC. The common AD632 and MPY634 devices consist of one feedback line (W), two ground lines (X2, Y2), two supply lines (+VCC, -VCC) and one… Continue reading Memo: Analog multiplier and voltage-controlled circuits

Memo: Active frequency filters

Frequency filters attenuate signals outside its band-pass thresholds. There are two flavors of frequency filters: active and passive. Active filters have op-amps and offer amplification, as well as impedance matching functionality, of the output signal. Passive filters are simple R-C-L networks without any op-amp. Band-pass and Band-stop construction A band-pass filter is defined as follow: A band-pass… Continue reading Memo: Active frequency filters

Memo: One-shot timer and op-amp filters

Integrators and Differentiators are basic building blocks of analog computers. They enable summation and subtraction operations (hence, the core component of them is called "operational" amplifier). For multiplication, multiple integrators are used in parallel, along with exponential and logarithmic elements (non-linear op-amp circuits), to achieve the effect via the following transformation: ln(ab) = ln(a) +… Continue reading Memo: One-shot timer and op-amp filters

Memo: Schmitt trigger

Hysteresis definition is as follow: the phenomenon in which the value of a physical property lags behind changes in the effect causing it, as for instance when magnetic induction lags behind the magnetizing force. In asymmetric bipolar power supply (such as those created by elevating a virtual ground from unipolar power source), the hysteresis can… Continue reading Memo: Schmitt trigger

Memo: Op-amp’s gain factor and noise problems

First, here's a quick cheatsheet on closed-loop gain factor for inverting and non-inverting amplifiers. The gain of inverting amplifier is given by the resistance R2 across the feedback loop divided by the resistance R1 across the forward input. A = R2/R1 Meanwhile, the gain of non-inverting amplifier is given by A = 1 + R2/R1 as… Continue reading Memo: Op-amp’s gain factor and noise problems

DIY Memo: ESP8266 v1 hookup

Tonight marks the third time I forgot how to hook up this wifi module already, I might as well leave a memo here for my forgetful future self. This is the hookup instruction for ESP8266 v1 using CP2012 and Tera Term software Things to know: 3.3 VDC source RX and TX can accept 5V logic level without problems (so… Continue reading DIY Memo: ESP8266 v1 hookup