100Vdc to 5Vdc 3 Amps Convertor ( Transistors Base)

100 VDC to 5 VDC (3A) Transistor-Based Step-Down Converter

Project Overview

This is a reliable, transistor-based linear step-down DC-DC converter designed to step down a high-voltage direct current input of 100 VDC to a stable 5 VDC output capable of delivering up to 3 Amps of current.

Key Specifications

• Input Voltage: 100 VDC

• Intermediate Voltage: ~15 VDC (pre-regulated stage)

• Output Voltage: 5 VDC

• Max Output Current: 3 A

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• Key Components & Working Principle

  1. • 1. Power Transistors (MJE13007 / MJE13009):

       These high-voltage NPN transistors act as the main series-pass power elements.

  2. Zener Diode Stage:

     • Zener diodes are utilized to establish a stable reference voltage and help stabilize the intermediate voltage stage (bringing the high input voltage down closer to a manageable ~15 VDC).

  3. Voltage Regulator IC (7805):

     • The intermediate ~15 VDC output from the transistor/Zener stage is fed into a standard 7805 linear regulator IC, which cleanly steps it down to the final, stable 5 VDC output required for your load.

  Circuit Advantages

  • High-Voltage Handling: Efficiently bridges a wide voltage gap safely using robust high-voltage transistors.

  • Stable Output: The two-stage reduction (transistor/Zener pre-regulator followed by the 7805 IC) ensures a clean and steady 5V output.

  • Reliability: Built with heavy-duty components designed to handle high thermal loads when properly paired with heatsinks.  

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TP4056 Module modification up to 5 Amperes (3.7V ,5 Amps)

Smart & Compact TP4056 Lithium Battery Charger Modification (Up to 5 Amps)

By default, the popular TP4056 charging module is limited to around 1A of charging current. If you want to scale up your charging capacity for larger battery banks without bulky hardware, here is a smart, compact, and cost-effective modification to boost the TP4056 charging output up to 5 Amps.

Required Components

You only need two standard components for this upgrade:

1. IRF3205 N-Channel Power MOSFET

2. 1K Resistor (1/4W)

Wiring & Connection Guide

To integrate the external MOSFET and scale up the current capability:

• Gate Connection: Connect the 1K resistor from Pin 7 (PROG) of the TP4056 IC directly to the Gate of the IRF3205 MOSFET.

• Power Path: Configure the IRF3205 to handle the high-current charging path from your input source to the battery, allowing the TP4056 to act as the intelligent control driver while the external MOSFET handles the heavy current load.

here TP4056 Module battery +ve and out +ve are common

Hybrid MPPT Solar Charge Controller

My new Hybrid MPPT Solar Charge Controller project  

Input Working Voltages from 20vdc to 80vdc, will be capable to charge both 12 and 24v Battery, 

with full hybrid functions also with Wi-Fi base dashboard 

Buck converter 30-70 Volts to 12Volts -24Volts (UA3845)

Buck converter 30-70 Volts to 12 Volts -24 Volts

A simple buck converter circuit which gives constant voltage with input voltages up 70 volt dc 

IRF3808 FET with UA3845 IC

         Visit YouTube:

https://youtube.com/shorts/5u_sx4aJsOg?si=rnHt8j91bn-W1Zwo

Bluetooth auto connect in MIT App

Bluetooth Auto-Connect in MIT App Inventor

When building Arduino, ESP32, or IoT hardware projects, selecting your Bluetooth module manually every time you open your app gets repetitive. By storing your device's MAC address in TinyDB, your app can auto-connect instantly on launch.

🛠️ How It Works

1. Initial Link: User selects the Bluetooth module once using a ListPicker.

2. Save MAC: On successful connection, the app stores the module's MAC address in TinyDB.

3. Auto-Reconnect: On Screen1.Initialize, the app retrieves the address and automatically connects in the background.

📱 Required Components

• BluetoothClient (Connectivity)

• ListPicker (For first-time device selection)

• TinyDB (Storage — to save the MAC address)

🧩 Block Logic Overview

• Screen1.Initialize: Read saved tag "BT_Address" from TinyDB. If present, call BluetoothClient.Connect using that address.

• ListPicker.BeforePicking: Set ListPicker.Elements to BluetoothClient.AddressesAndNames.

• ListPicker.AfterPicking: Connect to ListPicker.Selection. On success, save ListPicker.Selection to TinyDB under tag "BT_Address".

Sim800l Module Power Supply

Beside of very good and cheap Sim800l module , it is very hard to manage perfect power supply which it maintain the required voltage for th module.

Though it required up to 2 Amps at max burst , but it will work fine here  , capacitor will add more power stability to the module 

Battery will be also keep charging here, there is also cutoff circuit inside battery ,

you donot have the over charging issue for battery 

It will maintain power for SSim module while any interruption in input

1. Micro USB TP4056 Lithium Battery 18650 Charger Module 1A 3.7V
2. GSM Module
3. General Mobile set Battery 
4. 1000uf 6.3v Capacitor