# LED Chaser ( Single Chip Circuit )

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## Introduction: LED Chaser ( Single Chip Circuit )

There are zillions of LED chaser circuits and most of them use 1 integrated circuit for the sequence (e.g.,CD4017) and another for the clock (e.g.,555). Some go even further and use a microcontroller (overkill). This simple circuit uses only a CD4060 cmos I.C. for both functions. and can drive up to 800mA worth of LED´s (around 35 in parallel) for each of the 3 channels. CD4060 is a ripple binary counter and does not have decoded outputs as the CD4017, but we can easily decode decimal 0 with diodes ( DTLdiode-transistor logic gates ) . Decimal 1 and 2 are taken directly from the 2 least significant digits (LSD) . We will also decode decimal 3 to reset the counter back to 0.

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## Step 2: Circuit Diagram & Main Components

IC1: CD4060 cmos 14 stage ripple binary counter plus oscillator

Q1: BC327 PNP transistor (800mA)

Q2-Q3: BC337 NPN transistor (800mA)

D1-D4: 1N4148 diodes

R1-R3: 100ohm for 5 parallel LED´s. (recalculate for more parallel LED´s) - Even more LED´s with higher voltage supply voltage (parallel-series connected led´s).

## Step 9: Watch the Video. Thank You !

Subscribe to my YouTube channel ! SimpleTronic

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## 8 Discussions

great project

can i place your project on my website.

i'm working on a website which is related to electrical projects.

I will feel very proud seeing the project on your website. Thank you!!

I just hope one day I understand what you two very clever guys are talking about.

Great project, but beyond me yet

Thanks John :)

Aa microcontroller might be overkill, but it has some serious advantages over most discrete solutions. They're far smaller (such as the attiny10 in an sot23-6 package) and require way less external components. But their biggest advantage is the possibility to use them a a wide number of projects, allowing me to by them cheap in bulk.

However, this is great as a build-and-done, without the need of writing code and the equipment to flash it onto the controller. Perfect for beginners.

Thank you for continiously contributing awesome circuits to this community, imho you receive way to less recognition for you efforts. :)

Yes, attiny10 is a versatile microcontroller (I prefer PICs & will upload my designs soon) now, max output current of attiny is 40mA. For a LED chaser circuit you will need an output transistor/fet per channel unless you want a 3 led chaser. These transistors will need current limiting resistors for base & collector. In the end, you will be using as many components as me! .

Yes, I would love to have more followers (maybe my circuits are a bit complex to understand) but as long as I have at least one showing interest in what I have learned (in this case You) that´s enough for me ! Thanks!

I don't know I you knew that, but you can also use the internal pull-up as a npn transistor base resistor.

You would save 4 resistors, 4 diodes and on capacitor total. ;)

Yes, a nice feature of attiny is to enable pull-up resistors for individual port pins, now the value of these R´s can be up to 50Kohms and with a 5v Vcc supply, the current may be too low to fully drive a power bipolar transistor. It would be perfect though for a FET. You can even drive the fet directly from the port pin (configured as output) with pull-up disabled. ---|>|---

Oh yeah, I forgot the transistor shoud drive more than one LED. Even with a minimum gain of 250 (bc807/817-40) only 250*(5V-0.7V)/50k=21.5mA would flow through the transistor. Thanks for that hint!

Anyway I'd still add a high value pull-down to the gate of the mosfet to make sure it stays off during reset. A semi swiched state could damage the mosfet over long terms.