Using D-Type Flip Flops for Toggling

buildscc | 15 Oct 2011 | | tutorials

When using momentary pushbuttons it is common to want to store and then toggle state. There are a couple of ways to do this, for example, you could using a 555 timer, or construct your own latch/flip-flop. However, the 7400 series of integrated circuits has a few nicely packaged D-Type Flip-Flops which are appropriate for switching. The most appropriate is the 74xx74, which is a dual D-type flip flop with inverted and non-inverted outputs. There are other packages like the 74xx174 which is a quad, but you will need to use your own inverter, such as the 74xx04 or 74xx14, to invert the output. Also the packages with more than 4 D-type flip-flops often share a clock, which means that this method of toggling will not work with them.


1 Parts and Tools 2 Lets Put it Together! 2.1 Schematic Diagram 2.2 Step By Step 2.3 Video Tutorial 3 Resources 4 Credits

Parts and Tools

  • 1 74xx74 D-Type Flip-Flop (choose your logic level for your own project, LS is TTL logic and HC/HCT are CMOS).
  • 1 74xx14 Hex Inverting Schmitt Trigger(for debouncing)
  • 1 1k Resistor
  • 3 0.1uF Ceramic Capacitor (one for debouncing and two for the ICs)
  • Breadboard (or some other prototyping platform)
  • Momentary Push Button
  • Wire

Lets Put it Together!

Schematic Diagram

Step By Step

Video Tutorial



Christopher Woodall - chris.j.woodall

Meeting Minutes for 2011-09-28

buildscc | 28 Sep 2011 | | meeting-minutes


John-Nicholas Furst

  • Microsoft Imagine Cup
  • Microsoft Kinect
  • Solidworks

Valerie Young

  • Stairs

Kyle Brogle

  • How CTF Went
  • Who is doing stuff for Quinn?

George Silvis

  • Debian Knives

Kyle Brogle

  • Debian /Unbuntu Hackathon

Meeting Minutes for 2011-09-21

buildscc | 21 Sep 2011 | | meeting-minutes


Kyle Brogle

  • Clue dumps at MIT are starting soon, usually going to be tuesdays at 8pm. They’re held by SIPB, and they talk for next week is going to be on BIT coin, and if you’re interested, contact kyle.

Quinn - executive director of security for IS&T

  • “Key to security is people understanding things” hence want to start doing more awareness workshops. Information Awareness Week: one of things they really want to do is to set up some hacking demonstrations. Set up space in GSU (week of oct. 17th). Looking for things that can be done in 10min (to scare, but minimize pooping of the pants)

Kyle Brogle

  • CTF quals are this weekend! The qualification rounds will run from 8pm friday to 8pm sunday. If you’re interested, contact Kyle or John.

John-Nicholas Furst

  • BUILDS Calendar
    • Calendar is still password protected, should be finished (very) soon.

Valerie Young

  • Musical Stairs
    • Musical stairs will be starting up soon this semester, stay tuned for an email.

Danny Cooper

- Video Game Collective
	- If you like videogames and want to learn how to make one, stop by BUILDS on monday at 7pm.

Dan Ellis

  • 829 Studios Web Development
  • Contact if you’re interested


buildscc | 21 Sep 2011 | | about

This is a list of hostnames used in builds and their associated static ips.


{|- ! Hostname ! IP ! Description |- | builds-cluster-head || || SunFire V20z Cluster (Head Node) |- | builds-ares || ||Desktop (Windows 8) |- | builds-haku || || Desktop (Debian Stable Xfce) |- | builds-portal || || [[Portal|Ceiling laptop]] |- | builds-ashitaka || || Desktop (Debian Squeeze) |- | builds-door || || [[BUILDS Door Upgrade|Door computer]] |- | builds-patsu || || [[Lan-Tunes|Lan-Tunes server]] |- | builds-clunky || || Laser printer |- | builds-fesh || || creeper laptop portal #2 |- | builds-jorge || || creeper laptop portal multiplexer (woo) |- | builds-caiaphas || || creeper laptop portal #3 |- | builds-greenmachine || || [DOWN] In the greenhouse |- | builds-heman || || creeper laptop portal #4 |- | builds-zippo || || Crowell's Zippopotamus server [TEMPORARY, established 5/01/13] |- | builds-nicholas-hoult || || BkP CTF Website server [TEMPORARY] |- | builds-punpckldq || || Debian Squeeze VM on Ashitaka |- | builds-website || || Self-explanatory. Debian Squeeze |- | builds-pclmulqdq || || Ubuntu Precise VM on Ashitaka (for Zero) |- | builds-invlpga || || Debian Wheezy (for building packages) |- | builds-vrsqrtsnv || || Ubutunu Precise VM on Ashitak (for Chris) |- | builds-vmptrld || || Windows VM for Space Station |- | builds-popf|| || Ubuntu VM for John |}


iface eth0 inet static address 128.197.15.* gateway netmask


domain search nameserver nameserver nameserver

Meeting Minutes for 2011-09-14

buildscc | 14 Sep 2011 | | meeting-minutes


John-Nicholas Furst

  • Google Calendar
  • CS / ECE Coloqiums


Lockpicking (How did it go?)

Chris Woodall

Circuit Design Website

BUILDS Inventory

buildscc | 20 Jul 2011 | | projects


There are a few things I would like to inventory. One is computers / servers (this may be separate software as it might be specific to to computers). Not looking for anything to use to do managed administration, just inventory such as physical location and installed components (hd capacity, ram, processor, network interface, video card..)

The other more general inventory would be for things such as general items like tools (screw drivers, saws, soldering irons) and expendables (sand paper, wire, gloves, batteries). I don’t expect to inventory every last item and I am sure it is impossible to keep a perfect inventory in shared spaces but I think it will help multiple people. People have a hard time finding things a lot, even if they are in their proper place, just because they don’t know where that place is. This system could solve that. Secondly the officers like to keep BUILDS stocked especially with the expendable items. But sometimes we don’t know when things get used. If the inventory system had a way to report low / out of items it would be very helpful in keeping items stocked.


BUILDS is in a transition phase at the moment but we are going to use this as a chance to inventory our items as we move to our permanent room at the end of the summer.


  • Want:
    • Good web-based inventory software.
  • Options:


  • Determine inventory software
  • Install software
  • Inventory and add to software


  • John-Nicholas Furst (Project Leader)
  • Jeff Crowell
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