# 555 timer IC question

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#### phoenixSS

##### New Member
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?

#### ericgibbs

##### Well-Known Member
hi,
Is the 555 a TTL or CMOS type.?
What do you have connected to pin #3 of the 555.?
Dont apply 18V as a supply.

#### 4pyros

##### Well-Known Member
From what I know the output voltage of the system should yield 2/3 the Vcc.

No the output should be almost Vcc. What circuit are you using? What voltage do you need?

#### MikeMl

##### Well-Known Member
I'll bet he is trying to take the sawtooth output across the timing capacitor. That will be only 1/3 of Vcc peak to peak. The square wave at pin 3 will be about 8Vpp (into a high Z load) when Vcc=9V.

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