Control a furnace using a 3. 3V microcontroller. The furnace operates by connecting a common 21V AC `hot` line to one of two AC `neutral` output lines: Fan and Heat. When connected they have relatively low current flow, ~100mA. I`ve had some success using a TRIAC to do the switching - but I`m directly mixing the power sources by conne
Click here to download the full size of the above Circuit.
cting the DC battery negative to the common AC "hot" line. Battery negative/hot then becomes the reference at the TRIAC`s MT1, and I can switch the furnace on and off by sending +3V or 0V to the TRIAC base. Question is, is it kosher to mix power sources like this Do I risk an exploding battery, excessive battery drain, weird circuit behavior or anything like that If so, what would be the proper way to do this, to isolate the circuits I have no clue, but google shows some circuits setup in this manner. I`ll let someone else give an answer to that. My question to you though, why no go for isolation and use a opto-isolated ssr or triac, and not bother mixing them at all Passerby Apr 2 `13 at 4:19 Don`t know too much about the opto-isolated options out there - photo-triacs and SSRs look promising though, thanks for the tip. The few SSR`s I had come across before were all high-voltage types. QuadrupleA Apr 2 `13 at 4:29 Many household-grade thermostats use low holding current mechanical relays for this purpose. I`ve always been amazed that they can maintain several years of battery life with this approach, but they do. I`d expect a triac would be cheaper, so perhaps there are surge or mis-wiring risks inherent in such applications. HikeOnPast Apr 2 `13 at 5:20 Some triacs, when controlled from a unipolar DC to the gate with respect to MT1, won`t always conduct when the AC cycle goes negative i. e. they`ll trigger during the...
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
characters left: