Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.
As for the motor, if an 5V supply can operate it with effort, then that would be the possible voltage, however some to require 6 or even 12 volts, that relay can still be used if a resistor is placed in series with the relay coil.
If the motor does operate better with 9 or 12 volt and not show any signs of getting hot to an difficult to hold in hand range, then that would be an capable voltage, all tho if 5 volts gets an adequate result that would be acceptable in motor operation then that would be best for less power to heat dissipation.
The motor can be wired direct to the supply power to observe the results. Tho would limit the power to 12V max just in case.
:For Power supply larger than 5V: such as 12V or 9V. Again a 9V battery only gives reasonable current for a short time, and it often does vary from battery to battery even if the same manufacturer and time stamp states the same, no 2 are alike metaphor.
Tho, for 12 or so volt supply, an 12 volt relay would be suggested.
As for the 5V relay at 12 volts an 100R resistor to the relay coil in series would work to bring the current down from 170mA down to the relay coils preferred 70mA, an 1 Watt 100R resistor would be required to dissipate some heat as the resistor would be at half its power rating at 12v with the motor wired in series, about 500mW or so power dissipation for operation of the 100R resistor.
I assumed the motor to have a low resistance coil in use for the example of choosing a resistor value for a 12V supply.
the motor can also be resisted, tho I would not be aware of an decent value to suggest as I am unaware of the end use of that motor, the operation power requirement, the higher the series resistor - the lower the current to the motor.
And with 12V supply if chosen, the Transistors Base resistor should be changed to 1k from IC pin 3.
1k would be near or at 8mA driving the Transistors Base near 9 V at the 555 IC pin 3 with an 12 volt supply.
Some 555 IS outputs on source, pin 3 in this ones example places lower voltage out than the Rail supply, typical 2-3 Volt loss, so at 5V supply the output is 3.3 or so Volt.
with a 9 volt main supply use? an 50R resistor of a power rating of 1/2 Watt to relay coil in series, and a Transistors Base resistor of 600R from IC pin 3 would work, about 8.4 mA with avg 6volt out of pin 3 with 9V supply.
However the main power supply is up to you and overall the lowest rated parts requirement would state otherwise, the relay shows to be the lowest part in that circuit at 5 V. The 555 IC, if I am looking at the correct datasheet, (many manufacturers for these chips) Texas inst types and some others state 16V max recommended power for the 555 IC supply.
The Transistor has an listed max of 40V from Collector to Emitter, and an Collector to Base blocking ability of 60V ( only for very brief surges)
Overall, if you can use an 5V or near that supply because of the relay, then that's an suggestion for an supply to use if avail. If not then the resistor values above can help get the parts to function. all be it at 12 V a bit warm if the parts are not rated for 12v..Lots of toy car motors similar to that one are avg 4-6 volts avg 4 AA batteries for those.
Overly if the Supply is 5V, then yes, the 300R will be fine at just about 8mA at the Transistors Base. with the 555 Ic pin 3 placing around 3.3V to the Transistors Base.
I am using the devices 5V 100ma high current use typical value to overly assume the typical voltage on the Out pin 3 to be at or near 3.3V, tho the Ic can source 200mA thus I am pacing an ideal on the voltage being near to at 3.3v even with only 8 mA being sourced to the 2N3904 Base. This is an Datasheet PDF, tho not likely to be that Chip by manufacturer, so the data reliability would be listed as low. none the less, this is an adequate example if you do not all ready posses a datasheet for that 555Ic that you have, again example only.
:Edited: Above powered with an 5 volt supply as example to acquire the 3.3v comprehension.
If the relay does turn on and yet the motor not, then the motor may be requiring more power such as needing 12V as was thought of with that unknown motor, current rating and voltage rating.
If the relay does nothing then the resistor could be dropped to 300R and then tested when on the 9V supply to see if the relay responds then.
The pins and wires are in the correct places, tho with the relay turning on at powering the circuit? And the motor running.....
Remove the resistor from the 555 pin 3 to the Transistors Base, that 620R, then power the circuit and observe the results whilst checking the 555 Ic for temperature, if the 555 stays cool And the relay and motor runs, then the NPN Transistor has an issue,
If the 555 gets warm with the resistor removed, then somethings up with the 555 Chip.
This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
By continuing to use this site, you are consenting to our use of cookies.
