555 - Revision history

Rational Point: /* Notes */

2026-04-08T15:32:28Z

Notes

← Older revision		Revision as of 15:32, 8 April 2026
Line 17:		Line 17:
	R9 is an arbitrary load resistor for the output, probably less than desirable.		R9 is an arbitrary load resistor for the output, probably less than desirable.

	We have produced a simulated oscilloscope trace using Ngspice <ref>ngspice - open source spice simulator https://ngspice.sourceforge.io/</ref> on KiCad <ref>KiCad: A Cross Platform and Open Source PCB Design Suite https://www.kicad.org/</ref>.		We have produced a simulated oscilloscope trace using Ngspice <ref>ngspice - open source spice simulator https://ngspice.sourceforge.io/</ref> and/or LTspice <ref>“LTspice® is a powerful, fast, and free SPICE simulator software…” https://www.analog.com/en/resources/design-tools-and-calculators/ltspice-simulator.html</ref> on KiCad <ref>KiCad: A Cross Platform and Open Source PCB Design Suite https://www.kicad.org/</ref>.

	[[File:Plot555-2026-04-06.png\|frameless\|none]]		[[File:Plot555-2026-04-06.png\|frameless\|none]]

Rational Point: /* Clocking the 555 */

2026-04-08T15:06:26Z

Clocking the 555

← Older revision		Revision as of 15:06, 8 April 2026
Line 7:		Line 7:
	The simple demonstration circuit depicted above right is probably the simplest external clock for the 555. Below we have hastily constructed a true precision “clock” using four off-the-shelf bipolar transistors and some auxiliary resistors.		The simple demonstration circuit depicted above right is probably the simplest external clock for the 555. Below we have hastily constructed a true precision “clock” using four off-the-shelf bipolar transistors and some auxiliary resistors.

	This circuit operates by charging capacitor C1 through resistor R5 only up to the trigger level of 2/3 the supplied voltage, and then discharging the same capacitor down to the threshold value of 1/3 the supplied voltage through resistor R2 only.		This circuit below operates by charging capacitor C1 through resistor R5 only up to the trigger level of 2/3 the supplied voltage, and then discharging the same capacitor down to the threshold value of 1/3 the supplied voltage through resistor R2 only.

	[[File:555-op-amp-ctl-clock.svg\|frameless\|none]]		[[File:555-op-amp-ctl-clock.svg\|frameless\|none]]

Rational Point: /* Clocking the 555 */ phrase

2026-04-08T15:05:49Z

Clocking the 555: phrase

← Older revision		Revision as of 15:05, 8 April 2026
Line 7:		Line 7:
	The simple demonstration circuit depicted above right is probably the simplest external clock for the 555. Below we have hastily constructed a true precision “clock” using four off-the-shelf bipolar transistors and some auxiliary resistors.		The simple demonstration circuit depicted above right is probably the simplest external clock for the 555. Below we have hastily constructed a true precision “clock” using four off-the-shelf bipolar transistors and some auxiliary resistors.

	This circuit operates by charging capacitor C1 through resistor R5 only up to the trigger level of 2/3 the supplied voltage, and then discharging the same capacitor down to the threshold value of 1/3 the supplied voltage through resistor R2 only ~~down to the threshold voltage~~.		This circuit operates by charging capacitor C1 through resistor R5 only up to the trigger level of 2/3 the supplied voltage, and then discharging the same capacitor down to the threshold value of 1/3 the supplied voltage through resistor R2 only.

	[[File:555-op-amp-ctl-clock.svg\|frameless\|none]]		[[File:555-op-amp-ctl-clock.svg\|frameless\|none]]

Rational Point: /* Notes */ refs

2026-04-08T15:04:30Z

Notes: refs

← Older revision		Revision as of 15:04, 8 April 2026
Line 17:		Line 17:
	R9 is an arbitrary load resistor for the output, probably less than desirable.		R9 is an arbitrary load resistor for the output, probably less than desirable.

	We have produced a simulated oscilloscope trace using ~~NGSPICE~~ on KiCad.		We have produced a simulated oscilloscope trace using Ngspice <ref>ngspice - open source spice simulator https://ngspice.sourceforge.io/</ref> on KiCad <ref>KiCad: A Cross Platform and Open Source PCB Design Suite https://www.kicad.org/</ref>.

	[[File:Plot555-2026-04-06.png\|frameless\|none]]		[[File:Plot555-2026-04-06.png\|frameless\|none]]

Rational Point: clock / notes

2026-04-08T15:01:17Z

clock / notes

@@ Line 1: / Line 1: @@
 The '''555''' is a ubiquitous "timer" chip used by electronics hobbyists and experimenters.
-[[File:555-op-amp-ctl.svg|thumb|alt=555 op amp demo|Simple Demonstration Circuit]]
 [[Category:Electronics]]

Rational Point: demo

2026-04-03T04:50:59Z

demo

New page

The '''555''' is a ubiquitous "timer" chip used by electronics hobbyists and experimenters.

[[File:555-op-amp-ctl.svg|thumb|alt=555 op amp demo|Simple Demonstration Circuit]]

[[Category:Electronics]]