Author Topic: DIY Electronics  (Read 3476 times)

DIY Electronics
« on: October 30, 2013, 10:53:56 pm »
Here are some of the homebrew electronic projects I've knocked up over the last couple of years.

I updated the lamps below to run on high power LEDs rather than conventional lamps, the front has 8 LEDs and is simply on or off. The rear has an on or flash mode, I set the flashing mode at a lower frequency than is typical for rear lamps as it's on Mrs B's bike and that's what she wanted.


P1020821 by Joe.Audax, on Flickr


P1020823 by Joe.Audax, on Flickr


P1020818 by Joe.Audax, on Flickr


P1020819 by Joe.Audax, on Flickr

The next photos are of the indicators I made for the wife's trike. She always complained that cars would not notice her hand signals so I used the same high power LEDs as in the above photos in a set of motorcycle indicator lenses to knock these up. Half of the gubins on the circuit board has nothing to do with the indicators but is instead used to produce an alert tone to remind the rider to turn them off after turning. I had a switch on top of the box holding the board and batteries that allowed the circuit to be switched into 'trailer mode', isolating the rear indicators and instead supplying the ones on the back of the child trailer she used to tow.


P1000073 by Joe.Audax, on Flickr


P1000074 by Joe.Audax, on Flickr


P1000078 by Joe.Audax, on Flickr


P1000076 by Joe.Audax, on Flickr


P1020152 by Joe.Audax, on Flickr

Kim

  • 2nd in the world
Re: DIY Electronics
« Reply #1 on: October 30, 2013, 11:00:08 pm »
Nice to see the 555s actually getting some use.  These days I'd take the lazy option and use a microcontroller.

I've got a 'brake' (actually a deceleration-of-rear-wheel, using a standard computer sensor) light that I made to fit into one of those mudguard rear lights in a remarkably similar manner.  It works well enough, but nobody understands what it means.  I keep meaning to re-program it as a standard blinky.
To ride the Windcheetah, first, you must embrace the cantilever...

Re: DIY Electronics
« Reply #2 on: October 30, 2013, 11:04:26 pm »
 :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup: :thumbsup:

 :D
If it ain't broke, fix it 'til it is...

Re: DIY Electronics
« Reply #3 on: October 30, 2013, 11:09:48 pm »
Nice to see the 555s actually getting some use.  These days I'd take the lazy option and use a microcontroller.

Yes, were I to do this again I'd use a PIC, especially I've since been given a PIC programer. Used it to knock up one of those RGB colour changing lamps which I built into the bottom of a cut glass vase for the mother-in-law.  The 555s are simple and easy mind.

Re: DIY Electronics
« Reply #4 on: November 01, 2013, 05:51:18 pm »
I haven't the foggiest what you lot are talking about, but I just love threads like this  :thumbsup: :thumbsup:
Bread of heaven, bread of heaven.

Re: DIY Electronics
« Reply #5 on: November 01, 2013, 06:42:56 pm »
These days I'd take the lazy option and use a microcontroller.
Yes, were I to do this again I'd use a PIC
As an old git I would stick with the simplicity (to me) of a 555.  I remember them coming onto the market and the flurry of applications in amateur electronics magazines.  Other than gate arrays and the like I've never used a programmable device in my life, professional or otherwise.  I was a general purpose analogue/digital design wally whose design days ended in the early 90s aged 40.

Re: DIY Electronics
« Reply #6 on: November 01, 2013, 08:06:55 pm »
Hi,

Good projects Joe B.

As it was so cold earlier this year and my toes get numb really quickly in cold temps' I lashed up some heated insoles for my cycling shoes. Worked reasonably well, certainly greatly extended the time I could ride before numbness / cramp set in.










Re: DIY Electronics
« Reply #7 on: November 25, 2013, 07:46:08 pm »
Nice to see the 555s actually getting some use.  These days I'd take the lazy option and use a microcontroller.

I've got a 'brake' (actually a deceleration-of-rear-wheel, using a standard computer sensor) light that I made to fit into one of those mudguard rear lights in a remarkably similar manner.  It works well enough, but nobody understands what it means.  I keep meaning to re-program it as a standard blinky.
That might explain the intermittent rear light you had on the Tunnel ride :-[ . My reflection is that it didn't behave in the way that I'd expect a brake light to, but I can't pin down exactly why.

Kim

  • 2nd in the world
Re: DIY Electronics
« Reply #8 on: November 25, 2013, 08:05:46 pm »
Nice to see the 555s actually getting some use.  These days I'd take the lazy option and use a microcontroller.

I've got a 'brake' (actually a deceleration-of-rear-wheel, using a standard computer sensor) light that I made to fit into one of those mudguard rear lights in a remarkably similar manner.  It works well enough, but nobody understands what it means.  I keep meaning to re-program it as a standard blinky.
That might explain the intermittent rear light you had on the Tunnel ride :-[ . My reflection is that it didn't behave in the way that I'd expect a brake light to, but I can't pin down exactly why.

Bicycle speed isn't constant, especially at low cadences.  Anything reacting to absolute speed will start to oscillate with the pedalling frequency at around a certain point.  The B&M rear lights that get brighter as you decelerate do the same.  I've tried to mitigate the effect on mine by setting it not to respond below a certain speed (which also stops it from coming on while you wheel the bike), but it still does it under the wrong conditions.

Combine that with the fact that something that's responding to changes in speed doesn't follow the same pattern as one that's responding to the braking controls.  It will light up in response to inreases in gradient, lossy surfaces, gusts of wind, etc while the rider is very visibly giving it full welly on the pedals.  This seems unintuitive when you're used to car brake lights.

Additionally, the way I built mine - using a standard bike computer sensor - means there's a worst-case lag of a whole wheel revolution before it lights up, and an arbitrary timeout before it goes out when the wheel is stopped (the B&M versions use the dynamo signal, which has a higher resolution, so presumably avoid this problem).  Again, this isn't congruent with what you expect a vehicle brake light to do.

TBH, I don't really think it's very useful.  It was an afternoon project to try out a new PIC programmer.
To ride the Windcheetah, first, you must embrace the cantilever...

Kim

  • 2nd in the world
Re: DIY Electronics
« Reply #9 on: November 25, 2013, 08:33:07 pm »
Battery pack for barakta's electric assist trike:





Ping 20Ah 48V LiFePO4 battery, BMS and auxiliary electronics, built into Rixen & Kaul rear carrier box.

Speakon connector (one of the posh reasonably weatherproof ones) for the trike power, XLR internally for the charger (60V 5A switching power brick, on the left).  IP67 illuminated main switch.




Two seperate weatherproof enclosures, mainly due to awkward size:

On the right, the SignalLab battery management system (Ping enclose this in shrinkwrap, which seems suboptimally robust).  I've tapped into the thermal cutout header to provide a remote shutdown switch, avoiding the need for a high-current isolator to turn everything off.  The 16 blinkenlights indicate when the series cells have reached full voltage.

On the left, a Turnigy 130A DC power meter (this only measures current flowing *out* of the battery, unfortunately, but is cheap, accurate[1] and draws minimal power), DC:DC converters to efficiently step down the 52V nominal (can reach 60V when on charge) buss voltage to 7.5V for the trike's dynamo lighting, and 5V for USB charging.  (The e-bike console is wireless and charges from USB, so it seemed like a good idea to integrate this.)



I've used a regulator board designed for power-over-Ethernet applications for the first stage converter, and the lovely Recom 78B5.0-1.5 regulator (a drop-in replacement for the 7805) to provide the 5V.  Crowbar circuit and fuses to give the converters a fighting chance if something bad happens.  There's a relay to latch the BMS shutdown in the 'on' position while the charger is connected (so it doesn't fail to charge because you forgot to switch it on), which also disconnects the power to the lights.

As ever, it's the tedious mechanical stuff that I've been half-arsed with.  I couldn't get encosures with transparent lids in an appropriate size, so had to cut holes and fix clear acrylic windows.  Cable-entries are a botch.  Hot-melt glue used to excess.

The battery itself I've mounted to a sheet of 1.5mm aluminium, which is free-floating on a layer of closed-cell foam at the bottom of the box.  It's a snug, rattle-free fit with the lid closed, and protects the battery from the screws and fittings on the inside of the box.


[1] With the disclaimer that it doesn't seem to register current until it's in the 100mA range or so, which means the quiescent power of the motor controller, electronics and bike lighting doesn't show up.  This is actually useful, as it means the elapsed time clock stops when the motor isn't doing work.
To ride the Windcheetah, first, you must embrace the cantilever...

Re: DIY Electronics
« Reply #10 on: December 01, 2013, 08:58:25 pm »
I'm slightly surprised to be the first to comment on the overwhelming awesomeness of the above.........ah, right......... everyone else overwhelmed.

Cable-entries are a botch.
Nope, absolutely essential on a RealTM bike.

Kim

  • 2nd in the world
Re: DIY Electronics
« Reply #11 on: December 01, 2013, 09:19:05 pm »
Cable-entries are a botch.
Nope, absolutely essential on a RealTM bike.

I mean I've just melted appropriately size holes along the edge of the enclosure with a soldering iron[1], rather than drill and use grommets to achieve a proper seal or anything.  There were too many different diameter cables going in different directions to make that an attractive proposition.


[1] Also a good way of carving squarish-holes in plastic, when the alternative is a *lot* of tedious drilling and filing.
To ride the Windcheetah, first, you must embrace the cantilever...

Re: DIY Electronics
« Reply #12 on: December 01, 2013, 09:22:17 pm »
I'm slightly surprised to be the first to comment on the overwhelming awesomeness of the above.........ah, right......... everyone else overwhelmed.


Nope, just hadn't seen it!

I second the overwhelming awesomeness.