Step-Up Power Supply Without a Transformer: The Feasibility and Applications
In the realm of power supply design, the traditional approach often involves the use of transformers for step-up voltage conversion. However, this isn’t the only means, as alternative methods, such as motor-generator sets, capacitors, and solid state inverters, can also achieve this. Let’s explore the possibilities and applications of a step-up power supply without a transformer.
AC and DC Step-Up Without a Transformer
While transformers are the standard for AC step-up, the same can be achieved for DC with other components. Motor-generator sets can step up both AC and DC voltages, although they are typically more complex. For DC step-up, solid state inverters offer a viable solution, capable of converting DC to any desired voltage.
The concept extends to AC voltage as well. Voltage doubblers or triplers are well-known methods for achieving this. An interesting old technology, the vibrator type supplies, was used in radio equipment for tube voltages, but they also utilized transformers. Although large rotary inverting gears for DC voltage conversion were once used in street car systems, they have since become obsolete.
Voltage Doubler Circuit Explained
Electronics often require a higher output voltage than the input voltage. A voltage doubler is a practical and efficient solution for this. The doubler utilizes capacitors to store and release voltage across them. Here’s a step-by-step explanation:
1. Charging the Capacitor: Connect a capacitor to a voltage source. Let’s denote the voltage of the source as V. The capacitor charges up to V. Therefore, the first capacitor now holds a charge of V.
2. Adding a Second Capacitor: Take a second capacitor and charge it to V as well. Now you have two capacitors, both at V.
3. Connecting Capacitors in Series: Connect the negative lead of one capacitor to the positive lead of the other. When measured across the two remaining leads, the voltage becomes 2V. This concept is easily scalable and can be implemented using high-speed electronic switches.
A practical example is the RS-232 standard, which requires at least 8-12VDC. Many manufacturers incorporated a charge pump voltage doubler directly into components like the LT1537 or MAX232E, saving both cost and space.
Conclusion
While transformers remain the most common method for AC step-up, DC step-up can be achieved using voltage doublers, solid state inverters, and even motor-generator sets. These alternatives offer flexible and efficient solutions, making them valuable in various applications, particularly in electronics and communication devices. Although complex, these methods provide a compelling alternative to traditional transformer-based designs.