Transistors Handbook vs 555 Timer & Oscillators Pro
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Transistors Handbook
This app serves as a comprehensive guide to transistors, offering detailed information on over 51,000 types. Users can search for transistors by name or power, view graphical schemas, and access datasheets. It's designed to assist in selecting and designing electronic circuits.
- Database of over 51,000 transistors
- Detailed transistor specifications
- Graphical schema and code information
- Search by name or power
- Online datasheet access
- Information on Silicon and Germanium transistors
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Transistors Handbook - Your Transistor Guide. This app will guide you to know, choose, select and design your next board masterpiece using that transistor you weren’t remembering. With this app you can update the transistor informations and share it with other app users. What is a transistor? (from Wikipedia): “A transistor is a semiconductor device used to amplify and switch electronic signals and power. It is composed of a semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current flowing through another pair of terminals. Because the controlled (output) power can be much more than the controlling (input) power, a transistor can amplify a signal. Today, some transistors are packaged individually, but many more are found embedded in integrated circuits.” The transistor is the fundamental building block of modern electronic devices, and is ubiquitous in modern electronic systems. Following its release in the early 1950s the transistor revolutionized the field of electronics, and paved the way for smaller and cheaper radios, calculators, and computers, among other things.” With Transistors Handbook you will se the design, the kind and all the aspects of more than 51.000 transistors, the application will provide the following info: - Kind - Graphical Schema - Code - Type - Material - Power - VCB - VCE - VEB - LC - FT - HFE - Note of the Transistor - Similar - Online Datasheet You can also use the embedded search engine to search a transistor for its name or power. The coverage of the transistors is about the complete catalogue of the Silicon and Germanium. The series included are:, PNP and NPN, series 10 ~ 12, 14 ~ 19, 25 ~ 28, 2A ~ 2D, 2G, 2H, 2N, 2P, 2S, 2T, 30, 35, 37, 38, 3N, 3O, 3S, 3T, 40 ~ 43, 45, 4N, 50, 52, 55, 56, 5N, 60, 63, 6N, 71 ~ 74, 7N, 80, 81, 85, 90, 92, 94, A1, A5, A7, A8, AC, AD, AF, AJ ~ AM, AP, AR ~ AW, BC ~ BF, BJ, BL, BN, BP, BR ~ BV, C0 ~ C9, CA ~ CE, CG ~ CN, CP ~ CV, CX, D1 ~ D8, DA ~ DD, DH, DJ, DK, DM, DN, DP ~ DT, DW, DX, DZ, E1 ~ E3, E5 ~ E7, EA, EC, ED, EF, EJ, EL ~ EN, EQ ~ ET, EW, F1 ~ F5, FA ~ FH, FJ, FK, FM ~ FQ, FS, FT, FV, FX, FZ, G2, G6, GA ~ GF, GI, GM, GP, GS, GT, HA ~ HF, HK, HL, HN, HP, HS, HT, HV, HX, ID, IM, IN, IR, IT, J2, J4, J6, JA, JC, JE, JF, JO, K2, K4, K9, KD ~ KG, KM ~ KP, KR ~ KU, L4, L5, LB, LD, LI, LJ, LL ~ LP, LT, LX, M1, M2, MA ~ MH, MJ, MM ~ MU, MX, MZ, NA ~ NC, NJ, NK, NM, NP, NR ~ NT, NX, NZ, OC, OD, P2 ~ P4, P6, P7, P9, PB ~ PE, PH ~ PO, PR ~ PU, PX, PZ, Q, Q5, R3, R5, R7 ~ R9, RC, RE, RJ, RS, RT, RV, S0 ~ S2, S4 ~ S9, SA, SC ~ SH, SK, SM, SN, SP, SQ, SS, ST, SV, SX, SY, T0 ~ T3, TA, TB, TD ~ TF, TI, TK ~ TN, TP, TR, TS, TV, U2, UC, UM, UN, UP, V1, V2, V4, V7, W2, WT, XA ~ XC, XP, XQ, XS, ZB, ZD, ZG, ZH, ZT, ZU, ZX, with volts, frequencies, power, HFE (gain), similar transistors and pin design. The list may not be exhaustive, if you find any transistor missing, let us know. *** Don't forget to check also our Mosfet Handbook application. The perfect companion of Transistors Handbook.
555 Timer & Oscillators Pro
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Master the design of oscillators and waveform generators using 555 timer integrated circuits, digital logic integrated circuits, operational amplifiers, and transistors. The application provides a comprehensive collection of over 130 tutorials and circuit diagrams, covering 555 timer circuits and practical applications, CMOS 4000 series logic oscillators, TTL 74LS and 74HC series oscillators, operational amplifier–based waveform generators, and transistor multivibrators. Designed for electronics beginners, students, hobbyists, and professional engineers, the app serves as a complete reference and learning tool for designing, understanding, and building oscillators, multivibrators, pulse generators, and waveform circuits commonly used in both analog and digital electronics. In addition to tutorials and schematics, the app includes built-in calculators for frequency, timing, duty cycle, and component value estimation, helping users quickly calculate and adjust circuit parameters. All topics are presented with clear circuit diagrams and detailed explanations. 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! Covered Topics: • 555 Timer IC Series • Astable, monostable, and bistable modes • Pulse Width Modulation (PWM) • Voltage conversion circuits • Sensor and external module interfacing • CMOS Logic Oscillators • CMOS 4000 series circuits • Astable, monostable, and bistable modes • Gated CMOS oscillators • TTL / HC Logic Oscillators • TTL 74LS series circuits • 74HC series logic oscillators • Astable and monostable modes • Operational Amplifier Oscillators • Sine wave generators • Square-wave pulse generators • Triangle wave generators • Transistor-Based Oscillators • Transistor-Based Astable multivibrators • Transistor-Based Monostable multivibrators The Pro edition provides additional tools for faster learning and easy navigation: • Full-text search across all lessons and components • Favorites for saving and organizing important topics The content is regularly updated and expanded with each new release, ensuring the latest tutorials and circuit examples are always available.
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Verdict
The clearest difference is update cadence: Transistors Handbook at fortnightly against 555 Timer & Oscillators Pro's every 2 months. Transistors Handbook also leads on price ($3.99 vs $4.99) and iOS requirement (11.4 vs 17.0). On 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
Transistors Handbook costs $3.99 and 555 Timer & Oscillators Pro $4.99 up front. Neither carries in-app purchases, so what you see is what you pay.
Transistors Handbook ships an update fortnightly, 555 Timer & Oscillators Pro every 2 months. The most recent releases landed on October 23, 2026 and October 25, 2026 respectively.
| Parameter | Transistors Handbook | 555 Timer & Oscillators Pro |
|---|---|---|
| Price | $3.99 — better | $4.99 |
| Rating | 3.9 (24 ratings) — better | — |
| Positive reviews | 27.3% of reviews | — |
| Number of ratings | 24 — better | — |
| Update frequency | Fortnightly — better | Every 2 months |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Paid | — |
| Devices | iPhone, iPad, iPod | iPhone, iPad, Mac |
| Requires iOS | 11.4 — better | 17.0 |
| Further details — not scored | ||
| Size | 22 MB | 22 MB |
| Age rating | 4+ | 4+ |
| Developer | Centro Studi Informatica di Danilo Priore | ALG Software Lab |
In-app purchases
Transistors Handbook
No in-app purchases
555 Timer & Oscillators Pro
No in-app purchases
Questions
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Is 555 Timer & Oscillators Pro free?
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