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I am using a 555 IC to get 10KHz-50% square wave.Everything goes as expected Except for large ringing(About 2V above the normal 9V high voltage) during the rising Edges of output.

I put 0.1uF and 10uF bypass capacitors at Vcc pin.

Is it normal to have this amount of ringing ? or I can improve the circuit to reduce this Ringing further.

Note:C3 is 0.1uF not 0.1F as in the schematic

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    \$\begingroup\$ First: can you post a schematic? Second: Bypass caps on the Vcc line won't effect the output ringing. Third: have you properly tuned your oscilloscope probes? \$\endgroup\$ – loudnoises May 4 '18 at 8:21
  • \$\begingroup\$ Okay I will post a schematic.And yes,I tuned my probes \$\endgroup\$ – Mohammed Hisham May 4 '18 at 8:27
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    \$\begingroup\$ What is the output driving, via how long a wire? \$\endgroup\$ – Brian Drummond May 4 '18 at 9:22
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    \$\begingroup\$ Are you really using a 100,000 uF capacitor as a decoupler? \$\endgroup\$ – Andy aka May 4 '18 at 9:42
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    \$\begingroup\$ No, Andy is right. C3 is 100 mF, or 100,000 uF as he put it. Also, Kelvin-Hertz is not a relevant unit to this discussion. \$\endgroup\$ – Olin Lathrop May 4 '18 at 10:50

First, make sure your 555 timer can handle a supply of 9 V.

Second, check how your scope probe is grounded. My guess is that you either left the ground floating, or connected it in the wrong place, like back at the power supply. Hold the scope probe ground clip right on the ground pin of the 555, and the tip right on the output pin. Most likely, you will see much less ringing.

In general, you have to pay attention to details in engineering. Your "Eh, who cares" attitude has no place here. In one small question you missed two important details already, with C3 being shown as 100 mF and the frequency being stated as 10 Kelvin-Hertz. Properly grounding the scope probe is another one of those details that matters.

  • \$\begingroup\$ KHz means Kilo-Hertz not Kelvin-Hertz.You're right details matter and I'm sure that the probe clip is connected to GND pin and the tip is connected to Vcc pin directly.The 100mF It was a mistake in the schematic but in reality it's 0.1uF \$\endgroup\$ – Mohammed Hisham May 4 '18 at 11:29
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    \$\begingroup\$ @MohammedHisham Nope, kHz is kilohertz. \$\endgroup\$ – Richard the Spacecat May 4 '18 at 11:30
  • \$\begingroup\$ the 555 timer i use can handle about 15V at Vcc pin \$\endgroup\$ – Mohammed Hisham May 4 '18 at 11:31
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    \$\begingroup\$ @MohammedHisham Olin is correct, using a capital 'K' would make it read as Kelvin-Hertz. Using a lower case 'k' is the correct way to do it, as Richard pointed out \$\endgroup\$ – MCG May 4 '18 at 11:35
  • \$\begingroup\$ Thanks for making it clear.But we learnt it 'KHz' in school. \$\endgroup\$ – Mohammed Hisham May 4 '18 at 11:51

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