555 Calc vs Operational Amplifiers Guide
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
555 Calc
This utility app helps engineers and hobbyists calculate resistor values for circuits using the Timer IC 555. Simply input frequency, duty ratio, and capacitor values to get the required resistor outputs.
- Calculate resistor values
- Input frequency
- Input duty ratio
- Input capacitor value
- Timer IC 555 circuit design
Read full descriptionHide full description
This App calculates registors value, when designing the circuit using Timer IC 555. How to (1) Input Frequency value. (2) Input Duty Ratio. (3) Input C1 Value. (4) Touch ‘Calculate’ button. (5) Registors value will be displayed. Note. * Set Duty Ratio to 50 ~ 99. * If you set Duty Ratio to 50, R1 value will be set to 0.
Operational Amplifiers Guide
Read full descriptionHide 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
Verdict
The clearest difference is update cadence: Operational Amplifiers Guide at every 2 months against 555 Calc's every 20 months. 555 Calc's advantage is iOS requirement (11.0 vs 16.0). On price, ads, in-app purchases 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
Both are free to download. Neither carries in-app purchases, so what you see is what you pay.
555 Calc ships an update every 20 months, Operational Amplifiers Guide every 2 months. The most recent releases landed on September 27, 2026 and September 19, 2026 respectively.
| Parameter | 555 Calc | Operational Amplifiers Guide |
|---|---|---|
| Price | Free | Free |
| Rating | 4.0 (3 ratings) — better | — |
| Positive reviews | 50.0% of reviews | — |
| Number of ratings | 3 — better | — |
| Update frequency | Every 20 months | Every 2 months — better |
| Ads | Yes | Yes |
| In-app purchases | No | No |
| Monetization | Ad-supported | — |
| Devices | iPhone, iPad, iPod — better | iPhone, iPad |
| Requires iOS | 11.0 — better | 16.0 |
| Further details — not scored | ||
| Size | 18 MB | 17 MB |
| Age rating | 4+ | 4+ |
| Developer | Jibiki Works | ALG Software Lab |
In-app purchases
555 Calc
No in-app purchases
Operational Amplifiers Guide
No in-app purchases
Questions
Is 555 Calc free?
Is Operational Amplifiers Guide free?
Do 555 Calc or Operational Amplifiers Guide have ads?
Which is updated more often, 555 Calc or Operational Amplifiers Guide?
Other comparisons















