Recently, I delved into researching electric smoke generator and was pleasantly surprised to discover their ready availability at budget-friendly prices. These devices see widespread use in film and stage productions, as well as in radio-controlled (RC) models. In essence, most electric smoke generators create copious volumes of fog (not actual smoke) by utilizing a specially formulated non-flammable fog fluid composed of distilled water and glycerin in precise proportions. Further exploration unveiled the existence of other smoke generators that rely on readily obtainable single or multi-color smoke pellets to generate genuine smoke with the aid of electric or thermal energy.
As part of my research, I placed an order for an electric aircraft smoke system from an online retailer. This compact smoke system is designed for electric RC planes and offers the convenience of toggling the smoke on and off via radio control. Operating without the need for a separate tank, this self-contained system utilizes distilled water and glycerin to produce smoke for the electric airplane. Unfortunately, there was a delay in the shipment of the unit due to an error on my part, which compelled me to defer the planned teardown process to a later date.
Here are the results of my alternative approach, which is rooted in the conventional concept of generating “smoke.” At the core of my rudimentary smoke generator, which serves as the engine, lies a combination of a Nichrome-wire heater and a small wick immersed in a reservoir of fluid. The Nichrome wire is wound around a small ceramic pole, and the wick is loosely draped over it. In addition to these components, there are additional electronic elements, including a small heater control circuit and a brushless DC cooling fan. The fan is positioned at the top of the enclosure to direct airflow into the internal chamber. Smoke generated from the fluid reservoir is expelled through an exhaust pipe located at the top of the enclosure. It’s important to note that this smoke system requires a separate battery or power supply to operate.
Due to its widespread use as a resistance-heating element in household appliances like toasters, fan heaters, and hair dryers, Nichrome wire, which is an alloy of nickel and chromium, is both inexpensive and easily accessible. In my heater design, I opted for very fine diameter rings at the ends of the coil, as soldering Nichrome wire can be quite challenging (as depicted in the figure below). While fog fluid is readily obtainable from various sources, I chose to use baby oil as the fluid for my experiments. These experiments revealed that the amount of smoke produced varied depending on the absorbency of the wick and the heating element’s characteristics. For my experiments, I utilized a short segment of an oil lamp wick.
Since the wick serves as the conduit for transporting fluid from the reservoir to the heater, it’s essential to place the wick in a manner that facilitates efficient fluid absorption. If the smoke generator is producing insufficient smoke, consider repositioning the wick so that its tail is situated at the lowest point of the reservoir. This way, it can readily absorb any available fluid, as illustrated in the following figure.
Finally, the electronic circuit!
In this setup, a constant current source based on the LM317T (IC1) is employed to power the Nichrome-wire heater. The remaining portion of the circuit, centered around the BC557 transistor (T1), functions as a “heater on” indicator. In the initial design, an 80-mm BLDC cooling fan, sourced from a computer SMPS, was utilized as the blower fan. To ensure optimal circuit performance, a 12-V/1-A DC input is recommended.
With these components in place, you’re now ready to experiment with a heated wire, a wick, and some fluid or oil to create your own effective and dependable electric smoke generator!