I am brand new to electronics and have just started taking a beginning electronics class at the local college. My long-term interest is in controlling devices such as 120V/240V lights, motors, and/or solenoids.
In general, is it correct that large current devices are controlled by smaller low-voltage electronic components? In other words, a small transistor might be used to switch on/off a larger coil-based relay, which would, in-turn, switch on/off a light or motor.
TIA John
A relay is a good way for a beginner to get introduced to controlling "real world" electrical loads such as lamps or solenoids.
Let's say you have an HCMOS logic chip or a PIC operating with a 5V supply. The output pin can be programmed to be logic low (0VDC) or logic high (5VDC). The pin itself can only source or sink a few mA. Here's one way to use that logic output and those 10 milliwatts of power (5V * 2mA) to drive a relay which can switch a 100 watt, 120 VAC lamp (view in fixed font or M$ Notepad):
Fuse VCC VCC .-. ____ Line
- C| | 60 Watt 3AG 1A ^ C| o | C| - - '\ CRY1 | | \ 120 VAC | | o \ '---o | Logic Level | | Output | | ___ |/ '-------------------------o o-|___|-o-| 2N4401 Neutral
2.2K | |>..-. | | | |
2.2K | | | '-' | | | === === GND GND created by Andy?s ASCII-Circuit v1.24.140803 BetaThis will get you there, and you can buy all the components from Radio Shack. Their 275-240 relay has a 5VDC coil, and will switch up to 1 amp at 120VAC.
If you're going to be using hazardous voltages like 120 VAC, make sure you have your teacher or someone who knows what they're doing check your work before you plug anything in. Safety first.
Good luck Chris
Yes, that's often the case.
You're John Fields and I claim the $5!
Hi John:
Buy some triacs and diacs from the store. This part is used to control dimmer switches and drill motors. Its simple to hook up and uses 4 parts. Harold
solenoids
1 part:BTW, did the leading whitespace on Chris's print get deleted for anybody else (who's not looking at this at Google Groups)?
View with Courier font. .. Fuse .. VCC VCC .-. ____ Line .. + + .-----( X )-----|_--_|----o .. 1N4002| | RY1 | '-' .. - C| | 60 Watt 3AG 1A .. ^ C| o .. | C| - - \ CRY1 .. | | \ 120 VAC .. | | o \ .. '---o | ..Logic Level | '-------------------------o ..Output | Neutral .. ___ |/ .. o-|___|-o-| 2N4401 .. 2.2K | |>
.. .-. | .. | | | .. 2.2K | | | .. '-' | .. | | .. === === .. GND GND
beginning
solenoids.
by
Yes, large current or large wattage devices can be controlled by smaller device. An example of controlling 120VAC lamps from a low voltage circuit is here:
It's a chaser circuit where 4 120VAC lamps light in sequence.
-Bill
I guess Google Groups Beta munged the whitespace here. Try this (view in fixed font or M$ Notepad):
VCC VCC .-. ____ Line + + .----( X )-----|_--_|----o | |RY1 | '-' 1N4002| C| | - C| \ o ^ C| - - - \ CRY1 | | \. 120VAC | | o | | | '---o | | | Logic ___ |/ '------------------------o o-|___|-o-|2N4401 Neutral Signal 2.2K | |>
.-. | 2.2K| | | | | | '-' | | | === === GND GND created by Andy´s ASCII-Circuit v1.24.140803 Beta
Thanks to all for the "heads up", sorry for the confusion..
Chris
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