# 555 timer IC question

Discussion in 'The Projects Forum' started by PhoenixSS, Feb 6, 2011.

1. ### PhoenixSS Thread Starter New Member

Feb 6, 2011
2
0
Hi.

I am trying to create a mini signal generator using 555 timer IC.

I created the circuit using

C1 = 10e-6
R1 = 1000 Ω
R2 = 5400 ~ 55400 Ω ( I varied the R2 by adding a series of 2200Ω, 2200Ω, 1000Ω resistors and one 50000Ω potentiometer

From what I know the output voltage of the system should yield 2/3 the Vcc.

Since I am using 9V battery, it should yield ~ 6 volts. However, I am only getting around 4V. Please let me know what I can do to maximize the output voltage.

PS. also I know that input voltage is 4.5 V ~ 15V for IC timer. What would happen if I input 2 9V batteries and provide 18V in series?

2. ### jpanhalt AAC Fanatic!

Jan 18, 2008
5,699
909
Welcome to AAC.

Can you show us the circuit you have designed? Without it, C1, R1, and R2 have no meaning.

John

Feb 6, 2011
2
0
4. ### jpanhalt AAC Fanatic!

Jan 18, 2008
5,699
909
I think the main problem is that the voltage you are measuring is not the peak to peak voltage. Your voltmeter simply cannot respond to the frequency the device puts out. An oscilloscope will give you a truer picture of the actual voltage. John

5. ### SgtWookie Expert

Jul 17, 2007
22,183
1,728
In the schematic you referenced, C1 is on the CTRL pin; it stabilizes the threshold voltage. C2 is the timing capacitor.

If you have omitted C2, the timer will oscillate at a very high frequency, and your pot will have little influence over the output frequency since the capacitance from pin 6 to ground (the battery negative terminal) will be near zero.

As far as the "color chokras" - it's hogwash; snake oil, utter nonsense - a makeover of Royal Rife's pseudo-"research".

6. ### Wendy Moderator

Mar 24, 2008
20,772
2,540
We have several tone generator circuits in Volume 6, the experiments section. A lot of it I wrote.

I'm not a believer, like Wookie, but I always support experimentation. Life is funny, you usually tend to learn more from failure than success, and the act of trying something new is valuable.

The 555 produces about 1.2V less than the power supply for the top of its pulse, it is inherent in the chip design. 9V batteries also drop their voltage from 9V to 7V pretty fast, they are not discharged, it is also part of their design and most portable electronics is designed for it.

Jpanhlt is also correct, your meter isn't really designed for what you are trying to do.