Circuits

[DaOld Man]

I thought I would open a thread with circuits that are simple and may benefit us in our passion to re-create the Arcade experience.

First up is a simple circuit using a 555 and a handful of other components to control either DC motor speed (one direction only), or LED brightness.
LINK)

The circuit above is designed to control a motor, but if you replace the Q1 with your LED, it can control the brightness of the LED.
The 555 integrated circuit is a very common timer. (Available online or at Radio Shack).
The one rated for 4.5 to 16 volts is good for 200 MA.
If your LEDs draw more than that, just use a suitable NPN transistor to switch the power to the LEDs.
You can use the exact circuit in the link above, but just swap the motor in the circuit with your LED (with the appropriate resistor for your LEDs.) The diode around the motor in the above circuit is not needed, if you are controlling LEDs.

Got any useful circuits that you think would help out the group?
Post them here. We all need inspiration.

Edit: Here is the above pwm circuit, modified to control LED brightness:

[pixel.arcade]

Very interesting, inspiration is a keyword!

[DaOld Man]

Here is a very good H drive which is pretty easy to make.
This is not my circuit, it is posted here, with a lot of info on how to build it.
Caution! I highly suggest you use heat sinks on the power transistors, especially if you use PWM for speed control. I fried the transistors on my first build, without heat sinks.
The circuit:

[ed12]

hi
interesting thread
i have always loved the 555
i did a google 1 day to find a 555 timer circuit
and came across 45 circuit's u build with 555
i did not book mark it but thought i would point it out

ed

[DaOld Man]

Here is a very handy circuit I made a few years ago. Actually it is a modified wireless doorbell. Using a cheap battery powered door bell, I made an extension to my current doorbell.
I needed it for upstairs because i had a hard time hearing the doorbell (which is downstairs) when I was upstairs working on my projects.
It would have been a nightmare to route a wire from the downstairs chime to an upstairs one.
I could have but you know a lazy man comes up with an easier way to do the job.
Its a pretty simple circuit and works very good, providing that you remember to change the batteries in the chime part.
I removed the small 12 volt battery from the button that came with the wireless door chime. I made a small circuit that rectifies, filters, and regulates the AC from the downstairs door bell solenoid.
Then I taped the button to always be on.
When someone pushes the outside button by the door, the downstairs door bell rings and the wireless button is energized, sending a signal upstairs and ringing that one too.
The zener I used to regulate the power is 8.1 volts, it is what I had in my junk box at the time. It really needs to be 12 volts. The 8.1 volts decreased the distance of the remote chime, but it was ok for where I placed it.
The diagram below really sucks, (I couldnt find my original, this is copied off my blog site), if anyone is really interested in doing this, I will re-draw it better.

[DaOld Man]

Most modern autos these days have either a beeper to tell you that you left your headlights on, or they automatically turn off after a few minutes.
But older cars probably have neither.
Back in the day, I had a 1988 Firebird, which had neither. One night I left the lights on and the next day the battery was dead.
So out of necessity, I came up with this extremely simple headlight minder. The hardest part of this is connecting it to your car.
I used an small electronic buzzer. The one I used was polarized, if you connected it backwards it would not work, which was just what i needed.
I connected it to the radio circuit to get the ACC, and to a parking light "hot" wire, that way it still works if I just leave the parking light on, and if I need the lights on, the alarm is silenced if the key is turned to ACC.
If both lights and ACC are on, there is +12vdc to both sides of the buzzer. (Buzzer silent.)
If lights are off but ACC is on, the polarity on the buzzer is reversed. (Buzzer silent.)
If both are off, there is ground on both sides of the buzzer. (Buzzer silent.)
But if the lights are on and the ACC is off, there is +12VDC on the 'buzzer +' and ground (through the accessories) on the 'buzzer -'. Current flows through the buzzer and you are reminded to turn off the lights.
Diode is only necessary if the buzzer is not polarized, or if reversing the current on the buzzer might damage it.

[EightBySix]

Would be good to have a separate forum to collect useful electronics help such as this....

Just saying....

[BadMouth]

Would be good to have a separate forum to collect useful electronics help such as this....

Just saying....

This is the right place.  The name of the forum was changed to Automated Projects, which is a little better description.
It still shows up as mrotate in the list as far as I can see though.   

[DaOld Man]

Combination lock to open a 2 door garage.

[DaOld Man]

Very handy and simple timer circuit, using a 555 timer and 4 more parts.
I am incorporating this into my serial port drive, to ignore the flashing outputs until PC has had time to boot up.
Im using 5 volts for the supply, but I think it can go up to 17 volts. (Check specs on your timer to find out for sure.
The electrolytic capacitor will have to be selected by voltage too, good rule of thumb is at least 1.5 times the supply voltage.
I used a 220 uf 10 VDC elec. capacitor.
For Ra I used a 47K resistor in series with a 500K pot, so I could adjust the time. Time range is around 16 seconds to a little over 2 minutes.)
I will post the complete drive circuit when I am finished with it.
How it works:
When power is applied, pin 3 is low, or connected to ground.
The capacitor (C) charges through Ra. When voltage on pins 2 and 6 reach 2/3 of power voltage, pin 3 goes HIGH (+)
When power is removed, the capacitor discharges through the 1N4148 diode. (Quicker reset than it would be if it only had Ra to discharge through.) And pin 3 goes low.

I sent the guy that owns the website an email asking him for permission to use this, but email was returned as un deliverable.
If anyone objects to me using this, please let me know and I will remove it ASAP.
Here is a link to the site, it also has a handy calculator that allows you to choose the proper values for C and Ra, based on the time delay you need.

http://clarkson63.uk/555-timer/operation/frames3.html

[wemr97dl]

Got a question about RGB STRIPs
I want to control RGB Strips with a PAC64LED, looking online I found circuits on running them with Mosfets from an Arduino, not knowing anything about them I thought that these would work
http://www.ebay.com/itm/191850144579?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
here's the data sheet
 http://www.futurlec.com/Transistors/IRL540N.shtml
I put together the circuit but it doesn't turn on from the PAC64LED, using the default script, I know the brightness goes up and down so its probably not getting the full voltage
but if its not switching how will the RGB Color mixing work or fading??
Here's the circuit I was following, any help would be great

[DaOld Man]

Hello wemr97dl!
Sorry for the late reply, but I havent been around here for awhile.
Im not sure what is wrong with your circuit, looks like you have it wired right according to the data sheet.
I'm not real familiar with the arduino so I probably am not qualified to help. However, the only possible problem I can see is you are powering the leds from the arduino  power, could this not be hefty enough current wise?
perhaps try another 12 vdc power supply for the leds, of course you will have to connect the ground from the arduino to the extra PS ground.

[wemr97dl]

Sorry I wasn't more spacific I am powering the led strips from another source, and the ground is common but I'm not using an arduino I'm using a pac64led from ultimarc i don't know if it puts out enough power to turn on the mosfets , the circuit I posted was the example I used.

[DaOld Man]

I was thinking the same thing about the mosfet gate current may be too high.
You might try switching the gate with a small npn transistor. (Ex: 2n222)
Also, those mosfets are good for 26-36 amps. Do you really need something that big?
The pacled puts out 5 volts I think, maybe the voltage is too small for the mosfet gate? The smaller npn would also take care of that.

[wemr97dl]

Would a transistor switch fast enough for PWM FOR THE RGB COLORs

[DaOld Man]

Probably should, depends on the transistor's switching time.

[wemr97dl]

I contacted Andy at ultimarc about Mosfets and he sent me a print of his trackball lighting kit, he used p-channel and i bought n channel, I just need something big enough to handle 39 RGB leds at 12 v, which would be 13 per channel, he used BSH201: P-channel vertical D-MOS logic level FET, what specs would i need to look at when picking one out??

[DaOld Man]

I contacted Andy at ultimarc about Mosfets and he sent me a print of his trackball lighting kit, he used p-channel and i bought n channel, I just need something big enough to handle 39 RGB leds at 12 v, which would be 13 per channel, he used BSH201: P-channel vertical D-MOS logic level FET, what specs would i need to look at when picking one out??

Sorry about the late reply man, I really need to start showing up here more often. (Life, leave me be!)
I would follow andys advice, he knows what he speaks of. (I forgot those cards put out a negative signal to turn on the load. )
Hows this project coming along?

[wemr97dl]

Waiting on mosfets right now for the RGB Strips, but leaving for Vacation in a few days so I wont get back to it for a few weeks.

Here's a link to my project.
http://forum.arcadecontrols.com/index.php/topic,144775.0.html#lastPost


All that is left cabinet wise is Some button inserts for the start buttons and the Plexi for the monitor.
Got to get the RGBs running and start playing with LEDblinky and CPwiz for the second monitor, almost there