May 12 2017

Let’s combine a cheap wireless doorbell with a century-old phone

By Max

We recently (ish) moved into a new place, a big old victorian in the Haight.   There was no doorbell for our unit, so we did what you do and bought whatever the first result was for ‘wireless doorbell’ on Amazon.   About the same time, the Rents were doing some spring cleaning and gave me the wall phone above, because I guess they didn’t need it anymore.  Which raises but does not answer the question of why they needed it in the first place.  So when I have a few drinks and buy random technological artifacts on eBay, there might be some precedent for that.  Anyway, the preset ringtones on the doorbell were pretty hideous, and I thought why not class it up and make the phone ring when someone presses the doorbell instead?

If you want the YouTube video version of this, that’s here.

The Phone: This is probably 1915 or so.  The case is oak, the metal parts are brass.  You would ‘dial’ by clicking the receiver hook up and down which would summon a human operator, who would connect your call for you.

In the upper compartment on the right is a hand crank you would use to generate the voltage to send your voice back to the phone company.  Unfortunately that dynamo part is long gone, but the hand crank is visible on the right side.  In the lower compartment, clockwise from bottom left, is the Arduino, the wireless receiver from the doorbell, the high voltage circuit, and some perfboard to tie everything together.

For the high voltage circuit, I found this circuit on the Sparkfun site, which they were nice enough to open-source.   There’s a boost converter that kicks the 5V up to about 55V, and an H-bridge that allows you to switch the direction of the voltage through the solenoid.  I built the circuit and it worked, although if I was doing it again I might have gone for something that did the full 90V–  The ring could be a little more musical, and I think that might be because the clapper doesn’t have enough oomph to strike the bell cleanly.  On the other hand, it’s plenty loud as it is.    Here’s the circuit:

I also wired up the handset piece to play a dialtone when you pick it up off the hook.   Which has a practical purpose in confirming the processor is up and running, but mainly for fun.

The Doorbell: I opened up the receiver unit.   I was expecting to have to kind of kludge together the entire doorbell with the ringer circuit, but I noticed that the RF part of the board is a separate unit and just soldered onto the main logic board (at top):

The receiver circuit appears to be a buyout, which is ideal assuming I can figure out what the communication protocol is.  I did a search for the IC number, PT4303, and found a datasheet which told me it’s just a heterodyne, i.e. it’s just amplifying the signal to be decoded elsewhere.  Also that the chip is 5V tolerant, which is very convenient as I wanted to run this whole thing off a USB charger.

I hooked the receiver up to the oscilloscope and started poking at the transmitter while pressing the doorbell switch.   And found a digital signal on one of the transmitter pins (yellow), which was also showing up on the receiver data line (blue).   Bingo:

On the left is random noise, but as soon as I hit that button there’s a repeated digital pattern.   The pattern is either long-short (0) or short-long (1), in my case as you can see above the code was 00010011110010000.

For power, I wanted to use the vintage-style cloth-wrapped cable, but I also wanted to power it off USB.   I grafted a USB cable onto it and used the charger for my prior phone.

The Code: I used this library (that link does a good job of explaining the signal), although my timings were different so I guess there are slight differences in model.   If you want my arduino sketch (which includes the code to ring the phone and also generate a dial tone signal when the receiver is up) and also my Eagle file that’s here.

Here’s a video walkthrough I did.   Sorry if the camera work/narration is not the best.

If you enjoyed this or found it useful, be sure to leave a comment below.  Thanks for reading!

Sep 4 2016

Parklet Design Assignment

By Max


Another project I did for my Arch 134 class.  The assignment was: Design a parklet!


I started with the Tenderloin neighborhood in San Francisco where I lived at the time (life has changed drastically in the last two years!).  Typically parklets provide some kind of public amenity, an eddy to step out of the stream of pedestrian traffic.  If you put a parklet on Eddy street it would immediately become a venue for people to do all the things that you don’t want them to do, but it’s not like the neighborhood doesn’t have unmet needs.


So, I get it.  We don’t want to pay for public restrooms for homeless people.  In addition to the considerable expense associated with operating a high-traffic public restroom, it requires constant vigilance to make sure the facility is actually being used as a place to do your business, not your “business.”  Actually I’m not sure which usage would get the euphemism quotes, but anyway my point is, whether you want to pay for this or not, you’re going to pay for restrooms for homeless people.

Have you been to the main San Francisco Library at Hyde and Grove?  It’s a nice enough library, in an inoffensive 90’s postmodern way.  It’s also the only available public restroom in a 1/4 mile radius, and so the restrooms are always packed with people who don’t have another option, and have to constantly patrolled by security officers to keep the chaos to a low roar.  The streets east of Larkin and south of Geary are full of evidence that this facility isn’t nearly enough to meet demand.  So I decided to design a parklet around public restrooms.


I placed the parklet between the current day-use public restrooms at the Public Library, and the current after-hours restroom, the Lawrence Halprin-designed fountain in the middle of U.N. Plaza.  I like that this location breaks up the formal scenic view between U.N. Plaza and City Hall in a somewhat obnoxious way.

Map Capture with markups

Programming and Design

In addition to providing public restrooms, I wanted to provide public showers.  I included a micro-retail space as well, since I figured that there would have to be some kind of revenue-generating function as well to keep the whole thing going.  Using shipping containers would make it easy to set up and move.


Access to shower/toilets are via facebook check-in.  I think that sets a balance between the desire for these facilities to be available for all (facebook accounts can be created for free at the adjacent library), and the need to control access to prevent non-sanctioned use.

floor 1

The first floor incorporates three toilets, the stairs to the second level, and the handwashing station.  I was imagining the back wall behind the stairs as some kind of mesh or grillework, to keep the space open and ventilated.

floor 2

The second level is showers, and would be at about eye level to the adjacent statue of Simón Bolívar, and would have nice views on City Hall.    Also included on this level is a micro-retail, to provide some income to pay for operating costs.  Placing all of this on the second level allows access control after hours, versus the restrooms that are envisioned as 24-hour facilities.


This was a class project done over a weekend, so think of it as a sketch rather than a 100% build-able proposal.  But, if you’ve walked by the Tenderloin Pit Stop on Ellis St, you can see that this sort of thing can work.  Similarly, Lava Mae is doing fantastic work upcycling retired transit buses to mobile shower units.  It’s a simple way to improve the quality of life for everyone that shares the city.




Nov 28 2015

West Berkeley Public Library: A Case Study in Zero-Net Energy Lighting Design

By Max


I wrote this article on lighting design strategies for zero-net buildings for the Journal of Green Building.  As a case study, I used my West Berkeley Public Library project, for which I won an Illumination Award of Excellence.  It’s written for owners and architects that are looking for practical strategies to lower the energy density from lighting in their projects, and some of the issues that can crop up when you are trying to integrate architecture, electric lighting, daylighting, and lighting controls as one cohesive unit.

Hope you enjoy it!

West Berkeley Public Library: A Case Study in Zero-Net Energy Lighting Design

Nov 27 2015

Window-Box from Redwood

By Max


I made this windowbox.  In the past, I haven’t been satisfied with my efforts at woodworking, so I went slow and tried to really work on the fundamentals.  And hey, turns out everything is a hell of a lot easier if you have the ability to do things like cut to a line with a handsaw, and make boards square and true.  So I got pretty good with hand planes, chisels, scraper cards, and learned how to re-cut and sharpen saw teeth so that I could make a handsaw functional and sharp again– I had broken a bunch of teeth on mine and they were the induction-hardened type that you can’t sharpen.  I also made some tools like a depth gauge and a marking knife:20151026_221351

It’s made out of redwood, which is cheap and rot-resistant, and also has a really pretty grain I think:

Redwood Grain

Using a scraping card is easier than sanding and gives a much better finish.  That shimmery effect is caused by the grain switching directions, and so it was quite challenging to work with the handplane.  I have a contractor-grade Stanley #5 and a Craftsman block plane from the sixties that I got on eBay, so I took the time to set both of those up properly, and by the end I had them both singing.

Drainage is important for plant health and also can be kind of difficult to get right.  In addition, I didn’t want any excess water to drain near the house.  So the bottom panel of the box is on a slope, and there’s a 1/4″ trench drain the entire length of the box, which I then covered with mesh.  This has worked very well, I haven’t had any issues with root rot:

Window box drainIt was my first time attempting dovetails, and I didn’t get them perfect, but with four corners to do I got some good practice in:

Dovetail attempt #1 Dovetail attempt #2You can see the plugs where I had to insert shims because there was a gap if you look closely.  Also in the bottom picture the insert I made to cover up a really ugly knot in what is otherwise a nice looking piece of wood.

The bottom piece is held in with a housing dado on three sides.  I cut this by first running lines with my marking gauge, then working along with my chisel.  It worked okay, but the next tool that I’m going to make is going to be a depth router, because it was pretty tedious.


I have the old-style wooden sash windows and I made wedges that slot into the window tracks and the box so that it installs securely without any screws or fasteners:


Having done this I think I could take on some cabinets or a bookshelf with no problem– the time spent learning to use woodworking hand tools is a great investment.  I have about the most basic toolset possible, with a cheap saw, a 1/4″and 1″chisel, carpenter square, marking gauge, two inexpensive hand planes, and a scraping card, and I was able to get perfectly acceptable results.   It’s so great to use something that you’ve made every day.


Oct 9 2015

Rolleicord Shutter Repair

By Max


Thanks for nothing, Vivian Maier: So this starts with a trip to Chicago.  While we were there, we visited the Chicago History Museum and it turns out they’re a little butthurt about the whole Second City thing, but anyway the main attraction was a Vivian Maier exhibition, which blew my mind.

October 31, 1954. New York, NY

So long story short I got all inspired and bought a twin lens reflex camera on the ebay, a Rolleicord Va.  I’ve shot on medium format but I’ve never tried to work with a Nifty Fifty focal length before, but I like the way it forces you into an editorial mindset– the field of view isn’t very large, and you have to make choices about what you’re going to include.

But: Unfortunately like most cameras that are 60+ years old, the one I bought had a sticky shutter.  If I warmed up the shutter by test-firing a few times it would work fine, but if allowed to sit or in cold weather it would randomly stick open.  Which isn’t something that you want the camera shutter to do, for all of you budding photographers out there.  The remedy is a shutter overhaul performed by a professional camera repair technician, which will be a strange older guy with a wizard beard.

So I decided to get right in there and do the shutter overhaul myself, because what could go wrong.  While doing the overhaul I took a boatload of pictures so that I could get it all back together again, and since it seems a pity to let them rot away in my automatic backup folder, I’m posting them here, with sarcastic commentary and salty language.  This isn’t intended as a comprehensive walkthrough, but if you’re contemplating taking this on yourself  or perhaps need a little help getting humpty dumpty re-assembled, this may help.  If nothing else, it makes the $150-$200 that Beardo wants to charge you for a shutter CLA seem entirely reasonable.  Also, don’t fuck with wizards.

DISCLAIMER:  I’m just this guy on the internet.


Where is your god now?

But Seriously: So, I’ve got some experience with complex repair projects, and I felt like I was lucky to get through this one without fucking up a nice old camera.  So if you’ve got a camera you don’t want to ruin, totally just pay a pro to do this for you.  In my case, a CLA would cost considerably more than I payed for the camera, and I figured that even if failed the knowledge would be helpful in future projects, given my weakness for buying obsolete industrial crap.   All of the tricks I’ve learned taking apart other things to fix them and breaking them worse instead came in handy here: work in shifts so you don’t get sloppy, take lots of pictures, read the service manual and anything else you can get a hand on, etc.  Also, if you’ve ever broken something working on it, you remember what you were doing just before it broke?  So for each step, think about how much force you should have to apply to do what you’re trying to do, and if you’re applying that much force and nothing is happening, stop and re-assess, you’ve probably missed something.

Fuck it let’s go already: Assuming you know what you’re doing, I’ve omitted words like ‘carefully’ and ‘gently’ because like this entry was long enough already.  And with that, let’s get started, yeah?  Oh hey and there’s two service manuals you need, one for the Rolleicord/Rolleiflex model you’re working on, and a separate service manual for the shutter model you have.  Two different companies.

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