Comparison

Timer 555 Calculator Pro vs Operational Amplifiers Pro

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 Pro

Calculate parameters for monostable and astable circuits. Find component combinations for desired pulse width or frequency. Share circuit files via iCloud Drive or AirDrop.

Highlights
  • Calculate monostable pulse width
  • Calculate astable frequency
  • Find component combinations
  • Adjust component tolerance
  • Unlimited combinations (Pro)
  • Share circuit files
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 * Share file to iCloud Drive (For iOS8 or later) * Share file via AirDrop Additional Features in the Professional Edition * Unlimited number of combinations * Allow to change tolerance * No ads

About

Operational Amplifiers Pro

This app provides interactive calculators and reference information for designing and analyzing op-amp circuits. It offers step-by-step explanations and technical data on popular op-amp series, aiding students and engineers in circuit development and prototyping.

Highlights
  • Interactive op-amp circuit calculators
  • Step-by-step explanations and formulas
  • Reference data on op-amps and comparators
  • Support for 14 languages
  • Light and dark mode
  • Advanced calculators and circuit guides (Pro)
  • Full-text search (Pro)
Features
Read full description

Operational Amplifiers Pro is your essential tool for designing and analyzing circuits using op-amps. 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 Pro Version Includes: • Advanced calculators and circuit guides • Full-text topic search • Save favorite circuits for quick access 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 • Popular operational amplifiers description and pinout 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 and Square-Wave Generator • Generator with Adjustable Slope and Duty Cycle 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 Download now and power up your electronics work!

Screenshots

Timer 555 Calculator Pro4 screens
Operational Amplifiers Pro4 screens

Verdict

The call

The clearest difference is rating: Operational Amplifiers Pro at 5.0 against Timer 555 Calculator Pro's 4.7. Timer 555 Calculator Pro's advantage is price ($0.99 vs $4.99) and ratings volume (3 vs 1). On update cadence, ads, in-app purchases and monetization model 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

Timer 555 Calculator Pro costs $0.99 and Operational Amplifiers Pro $4.99 up front. Neither carries in-app purchases, so what you see is what you pay.

ReceptionRating · Positive reviews · Number of ratings

Operational Amplifiers Pro holds the better App Store score, 5.0 against 4.7. Both are backed by a comparable volume of ratings — 3 and 1 respectively.

UpkeepUpdate frequency

Timer 555 Calculator Pro ships an update every 3 months, Operational Amplifiers Pro every 2 months. The most recent releases landed on June 4, 2026 and September 16, 2026 respectively.

Scorecard4 real differences · 6 level
Timer 555 Calculator Pro versus Operational Amplifiers Pro: the parameters behind the verdict, then further details
ParameterTimer 555 Calculator ProOperational Amplifiers Pro
Price$0.99 — better$4.99
Rating4.7 (3 ratings)5.0 (1 ratings) — better
Positive reviews100.0% of reviews—
Number of ratings3 — better1
Update frequencyEvery 3 monthsEvery 2 months — better
AdsNoNo
In-app purchasesNoNo
MonetizationPaidPaid
DevicesiPhone, iPad, iPodiPhone, iPad, Mac
Requires iOS13.2 — better16.0
Further details — not scored
Size3 MB14 MB
Age rating4+4+
DeveloperSiu Yuen HoALG Software Lab

Customer experience

Timer 555 Calculator Pro

All ratings3 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews3 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

Operational Amplifiers Pro

All ratings1 ratings
Positive100.0%
Neutral0.0%
Negative0.0%

In-app purchases

None

Timer 555 Calculator Pro

No in-app purchases

None

Operational Amplifiers Pro

No in-app purchases

Questions

Is Timer 555 Calculator Pro free?
Timer 555 Calculator Pro costs $0.99, with no in-app purchases.
Is Operational Amplifiers Pro free?
Operational Amplifiers Pro costs $4.99, with no in-app purchases.
Which has better reviews, Timer 555 Calculator Pro or Operational Amplifiers Pro?
Operational Amplifiers Pro is rated higher. Timer 555 Calculator Pro averages 4.7 out of 5 from 3 ratings, while Operational Amplifiers Pro averages 5.0 from 1 ratings.
Do Timer 555 Calculator Pro or Operational Amplifiers Pro have ads?
Neither Timer 555 Calculator Pro nor Operational Amplifiers Pro shows ads.
Which is updated more often, Timer 555 Calculator Pro or Operational Amplifiers Pro?
Timer 555 Calculator Pro ships an update every 3 months, and Operational Amplifiers Pro every 2 months. Most recently, Timer 555 Calculator Pro was updated on June 4, 2026 and Operational Amplifiers Pro on September 16, 2026.

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