Shared Projects by Heisenbug

(Almost) as-laid-out for a demonstration for Engineering club in fall 2019…timely upload, right? At least I beat Halloween this year! The version 2.1 layout from this same schematic, and the original perfboard prototype both v2.0 & v2.1 came from, work great on 3-9Vdc. PCB meant for soldering practice for club members - eventually. V2.0 is as-yet untested but fully expected to work, IF they’re not too heavy-handed with the soldering iron on these fine traces. Only changes from this to the tested & working v2.1 are thicker traces, a few components moved/shifted to optimize space for 3 [irregularly-placed] mounting holes, power plug is centered on the side and one hole/pad grounded, and the trace routing to match the few component moves. Same dimensions/cost and BOM.

• ToUpdate - schematic & a v2.1 derivative link (eventually)

• 3 each 100K resistors (R1-R2-R3)

• 1 each 10K (R4), 4K7 (R5), 2K2 (R6), 100R (R7) - all can be 1/8w except this last one if running on >5v

• 22uF (C1), 47uF (C2), 100uF (C3)

• 2x 2n3904 (next to each other) + 1x 2n3906 (separate) - equivalents acceptable

• 2 LEDs that will look like the eyes you want, space onboard left for 10mm round jumbo type

• Other values and ratings non-critical - try to get close to the values I used for good timing effect, and ratings should meet or exceed intended supply voltage - then it will simply work.

May be updating/sharing the version 2.1 derivative of this before the month is out. All holes populated - no-via design - an astable multivibrator and a third transistor as a driver means it’s simple enough that this design technique is … (pun-intentionally) … viable.

Order arrived; first unit built has tested good and been programmed successfully. Pictures, BOM & schematic to be added soon.
Short & hacky, but I spent enough hours looking it over and improving it over a few days, so it ought to work !

Goals were to create an easy-to-prototype SOIC-8 wide/narrow to DIP-8 adapter for the ATtiny25/45/85 microcontroller family integrated with:
* an I©SP programming port using a keyed, shrouded header for IDC-type 6-pin ribbon cables, thus preventing reversed connections while easing re-programming (or attachment to other gadgets for I/O)
* a 5v LowDropOut regulator for more electrical reliability in rough service (e.g. damage to wires)
* an LED that won’t hamper programming, for power & heartbeat indication
* and a transistor driven output able to be wired as designed (or modifiable for other transistor types) for use in a 12v circuit which accepts 5v signals and tolerates 12v inputs

Application: virtual “button masher” with hybrid heartbeat power indicator LED - code not included, for now.

Known issues:
Mainly, there’s no mounting holes - neglected for reasons of size/cost - have to clip it in for securement & bolt that clip down to the enclosure it’s going into. Secondarily, that left end is seriously cramped and messy (though workable). Also, the tiny85’s label was left off the silkscreen (Name vs. Value would have to be manually moved to the other layer in Eagle).

Untested, but aside from odd dimensions at the top and slightly inconsistent 2mm pad edges, no known issues.

Tested & works great. Hand soldering is quite manageable, with the 0.65mm pitch IC pins of the FT232RL being the biggest challenge present.
A derivative of my v3 IC-only module. Same size/cost as v3.
The difference? This board is self-contained, and adds pads for a resettable fuse next to the USB header pads. (No, not specifically pads for a type-A USB male plug - you supply a cable and plug like this as I have done and attached via short pieces of 20-gauge wire, with good results. Uses standard USB order of +5v, Data(–), Data(+), GND / AKA the standard color coded red, white, green, black.)

Known issues:
* The data direction arrows point the wrong way relative to actual data flow… or you could say the TX and RX LEDs are in the wrong order due in part to a vague datasheet, but fixing the silkscreen arrows might be the easier fix.
* 6-pin FTDI-type header was designed for a female pin header and consequently has its drill size just a bit too small for standard square (male) pin headers - tested grinding down the pin corners to an octagonal shape, and it does indeed fit in there okay that way.
* Because of its double-sided nature - rather than riding on a single-sided carrier - it’s not very well suited for the slide-in bay on my Modul-Ar-duino. Perhaps double-sided foam tape plus a layer of rigid plastic over it may compensate for that.