Young entrepreneur in need of advice for electronic components of prototype

Thread Starter


Joined Feb 13, 2018
Hey guys I'm new to this website and forums in general, but I'm in need of some insight and direction as to what I need in order to make a product I'm designing work properly. I have a good idea of the components I need to make my idea work, but building a circuit board and putting all the pieces of the puzzle together is very far fetched without help. In my paranoia about product theft lol I'm going to be vague in describing my product. Essentially I want a box with 2 switches, an on/off switch and a warm/dry switch. When the 2nd switch is on warm I want 2 computer fans to operate at a low rate and a heating element to raise the temperature inside the box to 85 F and maintain it. Not too concerned about maintaining that temperature, as long as it's within 5 degrees I'd be fine. When the 2nd switch is on dry I want the 2 computer fans to operate at a high rate and a heating element to raise the temperature inside the box to 110 F and maintain it. I would also like to add a sensor that can assess when to turn off the dry setting once there is minimal moisture leaving the box. Any input on components I would need and how to wire the components would help. Thanks


Joined Sep 9, 2010
You’ll need an LM35 temperature sensor and an LM339 (quad) comparator to be your thermostat, and a MOSFET switch to control your heating element, if it’s DC. Everything running at 12V would simplify things. I’m not familiar with moisture sensors but you’ll obviously need one of those also. You might hack one out of dehumidifier. I’ve got a couple of those that operate a 120V switch directly. Add a handful of resistors, capacitors and some hookup wire and away you go.

Nothing you’ve mentioned yet is difficult, and there are multiple ways to do it.

Regarding fan speed, different fan types can be controlled in different ways. So the details will depend on the fans you choose. A typical computer fan can be controlled by PWM, and that’s a good choice.


Joined Feb 24, 2006
Here is some advice. Forget the idea that you will be successful with a single device. You will only be successful by creating hundreds of different devices over a career that will last four or five decades. Publish your work, let anybody and everybody copy it, so you can build your reputation for creativity. When you find a really good one, you build a few and sell a few. When the copycats show up, you are two to three steps ahead of them. In short don't waste a single moment of your precious time worrying about what other people are doing -- you have no control over it.

Whatever you do -- do not under any circumstances pretend to be or pass yourself off as an inventor. You're an entrepreneur and a businessman -- period, full stop.