Comparison

Timer 555 Calculator vs Operational Amplifiers Guide

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Timer 555 Calculator

Calculate monostable and astable circuits for electronics projects. Determine pulse width and frequency, find component combinations, and save/upload data. Supports multiple languages.

Highlights
  • Monostable circuit pulse width calculation
  • Astable circuit frequency calculation
  • Component combination finder
  • Save component values to CSV
  • Upload CSV via AirDrop/iCloud Drive
  • Multi-language support
Features
Read full description

This app is used to calculate monostable and astable circuit. Features * Calculate pulse width of monostable circuit * Calculate frequency of astable circuit * Find out combination of components making a desire pulse width in monostable circuit * Find out combination of components making a desire frequency in astable circuit * Saving component values in CSV file * Upload generated CSV files via AirDrop or iCloud Drive * Support English, German, French, Italian, Spanish, Portuguese, Japanese, Korean, Russian

About

Operational Amplifiers Guide

Features
Read full description

Operational Amplifiers Guide is your essential tool for designing and analyzing circuits using op-amps and comparators. Whether you're a student, electronics enthusiast, or experienced engineer, this app helps you create, calculate, and understand a wide variety of op-amp–based circuits with ease. Use it as a practical reference when developing projects, building prototypes, or studying amplifier configurations. The app also includes technical data on popular operational amplifier and comparator series — making it a handy guide for both design and selection. Available in 14 Languages: • English, French, German, Indonesian, Italian, Japanese, Polish, Portuguese, Russian, Simplified Chinese, Spanish, Turkish, Ukrainian, and Vietnamese — study in your native language! Key Features: • Interactive calculators for common op-amp circuits • Step-by-step explanations and formulas • Reference info on op-amps and comparators • Ideal for learning, prototyping, or quick checks • Light and dark mode support The application contains the following guides and calculators: Amplifiers • Non-inverting operational amplifier • Inverting operational amplifier • Inverting amplifier with T-bridge in OS • Differential amplifier • Differential amplifier with T-bridge in OS • Voltage repeater • Inverting voltage repeater • AC voltage amplifier • High Input Impedance AC Voltage Amplifier • AC voltage repeater ActiveFilters • Non-inverting low-pass filter • Inverting low-pass filter • Non-inverting high-pass filter • Inverting high pass filter • Bandpass filter • Gyrator Integrators and differentiators • Voltage integrator • Sum integrator • Integrator with signal amplification • Difference integrator • Double integrator • Voltage differentiator • Sum Differentiator • Differentiator with T-bridge • Differentiator with T-bridge made of capacitors • Difference differentiator Comparators • Comparator • Limiter • Limiter with zener diode at the input • RS trigger Attenuators • Non-inverting attenuator • Inverting attenuator Converters • Voltage-to-current converter with non-inverting input • Voltage to current converter with inverting input • Voltage to current converter with differential input Adders and substactors • Inverting adder • Addition-subtraction circuit • Non-inverting adder Logarithmic and exponential amplifiers • Diode-based logarithmic amplifier • Transistor-based logarithmic amplifier • Diode exponential amplifier • Exponential transistor amplifier Sine Wave generators: • Op-Amp Oscillators • Oscillator with Diode in the Feedback Path • Twin-T Network Signal Generator Square-wave pulse generators • Op-Amp Square-Wave Generator • Adjustable Square-Wave Generator • Enhanced Square-Wave Generator • Duty-Cycle Adjustment Triangle-wave signal generators • Nonlinear Triangle-Wave Generator • Variable-Symmetry Sawtooth Generator • Linear Triangle-Wave Generator • Adjustable Linear Triangle-Wave Generator • Variable-Symmetry Ramp Generator Popular operational amplifiers: description and pinout Popular comparators: description and pinout Download now and power up your electronics work!

Screenshots

Timer 555 Calculator4 screens
Operational Amplifiers Guide4 screens

Verdict

The call

The clearest difference is in-app purchases: Operational Amplifiers Guide at none against Timer 555 Calculator's 1. Timer 555 Calculator's advantage is ads (none vs shown) and iOS requirement (13.2 vs 16.0). On price, update cadence and device support there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. Timer 555 Calculator sells 1 one-off in-app purchase. Operational Amplifiers Guide asks for nothing beyond the download.

UpkeepUpdate frequency

Timer 555 Calculator ships an update every 3 months, Operational Amplifiers Guide every 2 months. The most recent releases landed on September 24, 2026 and September 19, 2026 respectively.

Scorecard3 real differences · 7 level
Timer 555 Calculator versus Operational Amplifiers Guide: the parameters behind the verdict, then further details
ParameterTimer 555 CalculatorOperational Amplifiers Guide
PriceFreeFree
Rating3.9 (8 ratings) — better
Positive reviews100.0% of reviews
Number of ratings8 — better
Update frequencyEvery 3 monthsEvery 2 months — better
AdsNo — betterYes
In-app purchasesYesNo — better
MonetizationFree with in-app purchases
DevicesiPhone, iPad, iPod — betteriPhone, iPad
Requires iOS13.2 — better16.0
Further details — not scored
Size3 MB17 MB
Age rating4+4+
DeveloperSiu Yuen HoALG Software Lab

In-app purchases

1 purchases

Timer 555 Calculator

One-time1
  • Unlock Pro feature$0.99
None

Operational Amplifiers Guide

No in-app purchases

Questions

Is Timer 555 Calculator free?
Timer 555 Calculator is free to download, with in-app purchases available.
Is Operational Amplifiers Guide free?
Operational Amplifiers Guide is free to download, with no in-app purchases.
Do Timer 555 Calculator or Operational Amplifiers Guide have ads?
Operational Amplifiers Guide shows ads; Timer 555 Calculator does not.
Which is updated more often, Timer 555 Calculator or Operational Amplifiers Guide?
Timer 555 Calculator ships an update every 3 months, and Operational Amplifiers Guide every 2 months. Most recently, Timer 555 Calculator was updated on September 24, 2026 and Operational Amplifiers Guide on September 19, 2026.

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