# Need Help with a Slightly. Different LED Flasher Circuit - Novice Here!

#### Bernard

Joined Aug 7, 2008
5,359
I took @AnalogKid , post #12 suggestions and put it on a bread board powered by 3 V Li cell but with only a bright red LED. SW-1 SPST NO, power , SW-2 SP2T, alternate LEDs, & SW3 SPST NO, both LEDs on. Will draw it up later if wanted.

#### Bernard

Joined Aug 7, 2008
5,359
First mistake, FET source goes to ground, no connection to D4. Resistors can be 1/8 W. I have all except for SWs, available for replacement cost.

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#### ninjagrips

Joined Nov 14, 2019
11
Is there not a way to send a PM on these forums?

I'm certainly interested, Bernard, though I may already have some of the components. I've got lots of different SPST momentary switches, not sure about latching, though. And not sure about double-throw, I'll have to check.

I'd definitely like to discuss it more, but can't figure out where the PM button is!

And Wolf, I like your schematic, as well. I'm just not sure I understand the ATiny IC thing. Would I need to get equipment to program it myself?

And I haven't forgotten about you, SamR! I like your schematic, as well! I'm trying to figure out what would be easiest for me to do!

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#### Wolframore

Joined Jan 21, 2019
1,536
Any idiot can count to 1!

There are a number of ways to program an Attiny, including another Arduino and some jumpers. I'm sure we can write the code for you which would take a whole 5 min. All you would have to do it flash it... Actually I have a bunch of little development boards I created for the Attiny series that already has mosfet switching and power supply on it. It would only need 6-7v supply and current limit resistors for the led. It has one output that isn't switched which can accept a switch input, so let's say you want it to do something else... like repeat or something else... you could add a pushbutton.

#### djsfantasi

Joined Apr 11, 2010
5,956
Is there not a way to send a PM on these forums?

I'm certainly interested, Bernard, though I may already have some of the components. I've got lots of different SPST momentary switches, not sure about latching, though. And not sure about double-throw, I'll have to check.

I'd definitely like to discuss it more, but can't figure out where the PM button is!

And Wolf, I like your schematic, as well. I'm just not sure I understand the ATiny IC thing. Would I need to get equipment to program it myself?

And I haven't forgotten about you, SamR! I like your schematic, as well! I'm trying to figure out what would be easiest for me to do!
And if you’re unfamiliar with micros to start with, there is a programmer into which you plug the ATTiny, and which plugs into an USB port on your laptop. Then, you use the Arduino IDE (which you likely used to write the code) to upload the code. Swap the ATTiny from the programmer to a socket on your circuit and Voila, it runs...

A programmer is available from Sparkfun and costs less than $20. ($16 the last time I checked). You’ll use it many times over, making it a cheap investment.

If you have several Arduinos already and can reliably wire them to be a programmer as well, then that’s an option. However, given your level of experience, I’m not confident that you can get this running easily. Hence, my suggestion for a plug and play programmer.

#### SamR

Joined Mar 19, 2019
1,639
Is there not a way to send a PM on these forums?
Click on the person's name or avatar and select start a conversation and you are in PM. Some folks have that option turned off if they don't want PM's.

#### ElectricSpidey

Joined Dec 2, 2017
804
I think you may need a minimum of messages to send a PM.

#### Bernard

Joined Aug 7, 2008
5,359
It used to be 10 posts- I think.
Seems like SW2 could be replaced by 2 SPST NO SWs.
Is'nt this a lot of trouble just to manually control 2 flashing LEDs?

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#### djsfantasi

Joined Apr 11, 2010
5,956
That’s why I like uC design... this is all you need. Actually take one led out on below.. it’s all in coding.

could be run at 3.3v, Vf of red and gr led should be about 1-6-2.1v

power up start blinking whatever you want.. then switch colors
do this as many times as you like
power down into low power mode and go to sleep or add a latching circuit and actually cut power

View attachment 192004
And using the Arduino IDE, there’s a library available to turn a pin into a capacitive switch. Saving you the space for an external switch. You just need a wire to/on the case.

#### eetech00

Joined Jun 8, 2013
1,786
Hello,

Here is a revised circuit.
If you use DPDT toggle or "Alternate action" button for "ON" switch, as well as the other switch types shown, it really simplifies the circuitry. The switches can even be DIP switches (witch looks like what is being used in the video).The circuit board can be a perfboard with thru hole parts for experimentation, or, a PCB with surface mount parts would make a tiny board for production. The flasher is set for an ON time of about 1 second.

eT

note-
Corrected simulation error.
Circuit remains the same and tested good.

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#### AnalogKid

Joined Aug 1, 2013
8,256
In #50, the DPDT lamp test switch can be replaced with a much smaller SPST switch and two 1N914 diodes.

ak

#### Bernard

Joined Aug 7, 2008
5,359
Note: 2 SR44W has same capacity as CR11108,& same height. LR44 about 1/2 the capacity & cheaper. If the height is slightly to much then 2- SR43W's = 8.4 mm H, @ 125 mAh.

#### eetech00

Joined Jun 8, 2013
1,786
In #50, the DPDT lamp test switch can be replaced with a much smaller SPST switch and two 1N914 diodes.

ak
Hi ak

I tried using two 1N4148 diodes (all I had) instead of DPDT switch but the LEDs did not light steady. They lit from "full ON flash" to "half ON flash"...they flash at about half brightness.
Otherwise, the TLC555, 2N7000 and LED's(2v@20mA) worked fine at 3V...as shown on post #50.

eT

#### SamR

Joined Mar 19, 2019
1,639
Something to note about the CMOS 555:
CMOS 555 A low power version of the 555 is available from many manufacturers and basically it is a CMOS version of the TTL 555 device. The CMOS 555 has the same pinouts as the TTL version and can be fitted into the same 8 pin socket but if the circuit needs more current than can be supplied by the CMOS version, it will not produce the same results. It is the low current capability of the CMOS version that will be the major reason why you cannot directly replace the TTL version with the CMOS version. It will operate from 1v (only some manufacturers) to 15v and will work up to 3MHz in astable mode. Current consumption @5v is about 250uA (1/4mA) But the major thing to remember is the output current capability. At 2v, the chip will only deliver 0.25mA and sink only 1mA. At 5v, the chip will deliver 2mA and sink only 8mA At 12v the chip will deliver 10mA and sink 50mA At 15v the chip will deliver 100mA and sink 100mA

#### Wolframore

Joined Jan 21, 2019
1,536
@SamR is that per pin or overall?

#### SamR

Joined Mar 19, 2019
1,639
Good question, all I had is what you see. My interpretation is that since it says both source and sink it is for Pin 3, the Output and Pin 2, the Trigger. I have a few different part numbered CMOS versions but never used them. When I was playing around with timers I used the NE555. I ran across that last nite while perusing some online PDFs and found one on timers. http://www.talkingelectronics.com/te_interactive_index.html Look for "50 555 Circuits A Free EBook" Lots of good tidbits on Hans' Timer.

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#### Wolframore

Joined Jan 21, 2019
1,536
Oh nevermind, I’m thinking of cmos 4xxx. Doesn’t matter so much for 555

#### eetech00

Joined Jun 8, 2013
1,786
Good question, all I had is what you see. My interpretation is that since it says both source and sink it is for Pin 3, the Output and Pin 2, the Trigger. I have a few different part numbered CMOS versions but never used them. When I was playing around with timers I used the NE555. I ran across that last nite while perusing some online PDFs and found one on timers. http://www.talkingelectronics.com/te_interactive_index.html Look for "50 555 Circuits A Free EBook" Lots of good tidbits on Hans' Timer.
hi

the circuit in post #50 uses a CMOS TLC555 timer. The drive transistor is a mosfet so the timer output drive current is not an issue.

eT

#### Bernard

Joined Aug 7, 2008
5,359
Some of the problems noted in post #50 were avoided in post # 42 by squelching action of
oscillator by R3 & D4, & FDD6530A with lower gate V appears to be a better SW than 2N7002.

#### eetech00

Joined Jun 8, 2013
1,786
Some of the problems noted in post #50 were avoided in post # 42 by squelching action of
oscillator by R3 & D4, & FDD6530A with lower gate V appears to be a better SW than 2N7002.
hi Bernard

what problems?

The circuit in post #50 works fine at 3 volts.
Luke is operating the device using DIP switches...

eT