ElectricDollhouse
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Dollhouse Lighting operated by Pi

Thu Feb 25, 2016 3:53 pm

Hello everyone,

I'm an absolute beginner but it's nice to be here as kindly suggested by the shop assistant at Maplins this morning. I am seeking advice if I may?

From searches online I think my project is comparitively basic but I'm still struggling to grasp electronics and it's technical jargon.

I make tiny dollhouses and would like to operate LED lighting and door open/close operation by way of a RC/wireless fob. My wishlist is:

1. A multi button RC to switch individual LED light on/off/dimmer.

2. Same RC to transmit to low voltage motors and cogs that will open and close dollhouse doors.

3. All the above to be powered by built in batteries in the Base of the dollhouse as opposed to plug in transformer.

Any suggestions and solutions will be greatly appreciated. Thanking you in advance.

Shane

tech-mech
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Re: Dollhouse Lighting operated by Pi

Thu Feb 25, 2016 10:19 pm

First remember the 3 Ps and we don't plan to fail we fail to plan. The way I see it you have several parts to what you want to do.

To open and close doors I would use servos, you might need to locate them below the house, in the attic, or under a cover on the side. Make test set ups to get it to work before you make the house. For lights you could use wearable LEDs, the ones from Adafruit are smaller then the ones from Lily pad. You could also use them for a fire place. If you want to make a haunted house look at piezospeakers, some are very flat. I know that 3D printing it the 'thing' but you could also use polymer clay for one offs.

I would use a micro controller instead of a RPi at the house end and a RPi with the official touch display for control. My choice would be a Propeller project board (about $25 USD). Check out Learn Parallax for lots of help in programming it. You can program it from a RPi in its native spin / pasm or in c / c++. The Pimoroni Propeller HAT would be a good development board.

There are many ways to communicate without wires and the RPi and Prop can do the all if you work at it.

Hope this gives you some ideas and help.

BMS Doug
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Re: Dollhouse Lighting operated by Pi

Fri Feb 26, 2016 10:25 am

ElectricDollhouse wrote:Hello everyone,

I'm an absolute beginner but it's nice to be here as kindly suggested by the shop assistant at Maplins this morning. I am seeking advice if I may?

From searches online I think my project is comparitively basic but I'm still struggling to grasp electronics and it's technical jargon.

I make tiny dollhouses and would like to operate LED lighting and door open/close operation by way of a RC/wireless fob. My wishlist is:

1. A multi button RC to switch individual LED light on/off/dimmer.

2. Same RC to transmit to low voltage motors and cogs that will open and close dollhouse doors.

3. All the above to be powered by built in batteries in the Base of the dollhouse as opposed to plug in transformer.

Any suggestions and solutions will be greatly appreciated. Thanking you in advance.

Shane

Hi Shane,

This is all fairly simple in concept, there will be many ways it can be implemented.

1a. Multi-button RC: 422MHz is your friend, there will already be a wide variety of multi-button RC transmitters, you can either pick one you like or build your own. If you build your own you could go as far as the touchscreen version suggested by Tech-Mech.
422MHz transmitter receiver pairs are very cheap.
Adding a Wifi dongle and running the dollhouse lighting from a webpage served by the Pi would also be possible, allowing a phone or tablet to control the lighting / doors etc.

1b. LED's: unless you are limiting yourself to one or two LEDs per button push you will need to use a transistor to switch the LEDs on (too much current for the Pi to handle). Not a big problem and can be added after you've proved the concept with a single LED per button push.

2a. as 1a.

2b. Motors: There are a wide variety of options, the safest route is the servos suggested by Tech-Mech but if you prefer other options they are available.

3. Shouldn't be an issue, there are plenty of options out there.

Unlike Tech-Mech I'd use a Pi for this. (An A+ or maybe a Pi0 (if you can get one) but use a B+ or Pi2 as your testing and development machine).
Advice:
Don't try to get it all working at once, do one thing first then expand it to add other functions.
Doug.
Building Management Systems Engineer.

PiGraham
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Re: Dollhouse Lighting operated by Pi

Fri Feb 26, 2016 10:57 am

If you want good life from batteries a micro-controller like an Arduino or Teensy with very low power modes is probably a better choice. If you wanted Bluetooth control check out Blueno.
You could use 433MHz radios with any device.
You could add a power control circuit to the Pi so it turns off after a few minutes of inactivity, but then you could have a 30s wait for it to restart, unless you go for "bare metal" but something like Arduino is probably easier to program.
If you can use a mains adaptor, or don't mind the limitations of a power switch and slow startup, then a Pi could do the job.

There are some really tiny stepper motors available that might do for doors. Micro servos are an option. In any case, you probably want a way to turn off the power to motors and light to save battery power.

ElectricDollhouse
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Re: Dollhouse Lighting operated by Pi

Fri Feb 26, 2016 3:28 pm

Hello tech-mech, BMS Doug and PiGraham,

Thank you all so much for taking time to reply and explain in great detail your suggestions, I am extremely grateful.

I shall print your replies, read them again several times and further research the purchasable items and take it from there.

The idea of a auto switch off power saving device is great. I guess there is the possibility of programming the lights to come on at a set time as well. Exciting stuff.

Again, thank you so much.

Shane

PiGraham
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Re: Dollhouse Lighting operated by Pi

Fri Feb 26, 2016 4:10 pm


BMS Doug
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Re: Dollhouse Lighting operated by Pi

Fri Feb 26, 2016 4:22 pm

PiGraham wrote:Motors like these might suit

Image

http://www.ebay.co.uk/itm/10pcs-Two-pha ... SwnGJWTuS5
Nice little motors!

Stepper motors in this application have a set of problems (not insurmountable) that you need to consider the solutions for before choosing them.

How will the controller (whatever controller you choose to use) know the position of the doors when it powers up?
(Easiest solution: Limit switches when door is fully open or fully shut).

Stepper motors will need a driver chip (plenty commercially available), choosing the correct driver ship will depend on the stepper motor.
Doug.
Building Management Systems Engineer.

PiGraham
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Re: Dollhouse Lighting operated by Pi

Fri Feb 26, 2016 7:33 pm

Limit or sensors are probably not required for doors. Just drive the motor enough steps to guarantee hitting a mechanical stop to "home" the door, then step back as many steps as you want. For fully open - fully closed just drive to the stops. The motor will simply slip.

You get smooth speed controlled movement.
Last edited by PiGraham on Sun Feb 28, 2016 6:04 pm, edited 1 time in total.

ElectricDollhouse
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Re: Dollhouse Lighting operated by Pi

Sun Feb 28, 2016 5:40 pm

Hi Graham and Doug,

Many thanks again. Those motors are unbelievable. I had no idea they came so small. This will open up more intricate opportunities. I looked at some other small electrical items the seller had which also look very, very useful.

Thank you again. Whatever your present projects are I hope you are enjoying success.

Shane

RDS
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Re: Dollhouse Lighting operated by Pi

Sun Feb 28, 2016 7:16 pm

Just out of interest - what voltage are those motors?

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GTR2Fan
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Re: Dollhouse Lighting operated by Pi

Sun Feb 28, 2016 7:41 pm

The voltage doesn't seem to be listed anywhere, but they're 10 for £1.99 delivered now, so killing a few experimenting wouldn't cost a fortune...

http://www.ebay.co.uk/itm/10pcs-Two-pha ... 1076192381

As one of their listed uses is inside digital cameras, we could probably hazard a guess at 3 to 4V?
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PiGraham
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Re: Dollhouse Lighting operated by Pi

Sun Feb 28, 2016 10:51 pm

RDS wrote:Just out of interest - what voltage are those motors?
Some of that type are listed as 3 to 5 V Lots to choose from.

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MattHawkinsUK
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Re: Dollhouse Lighting operated by Pi

Mon Feb 29, 2016 12:08 am

How many LEDs are you going to use? This would be good to decide early on because it will determine what options you've got to drive them.

My mum had an extensive 12th scale dolls house collection. I inherited her "Witches House" and unfortunately I didn't have room for the others! I made and sold accessories in the early 1990's and anyone who bought a 12th scale Harrods bike or wooden step ladder from the shop in Rochester probably ended up with my handy work.

I planned at some point to use a Pi to upgrade the lighting in the witches house. One plan was to use neopixels to "flicker" the fireplaces and simulate lightning. The house looks great with lighting and I wanted to have different settings perhaps with a few sensors and motors.

As with all projects I haven't had time to do anything but I'm pleased someone is trying to use a Pi in a dollshouse. I completely get it ;)
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RDS
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Re: Dollhouse Lighting operated by Pi

Mon Feb 29, 2016 10:21 am

Thanks GTR2Fan and PiGraham, I have ordered some.

Can they be driven directly by the Pi, or do they need some form of stepper motor driver.

PiGraham
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Re: Dollhouse Lighting operated by Pi

Mon Feb 29, 2016 10:58 am

RDS wrote:Thanks GTR2Fan and PiGraham, I have ordered some.

Can they be driven directly by the Pi, or do they need some form of stepper motor driver.
Motors are inductive loads that can generate voltages higher than the applied voltage and can draw higher currents under load so, even if they only draw a few mA don't connect them directly to GPIO signals.

This ebay ad gives some basic specs

20 Ohm 3 to 5V
That suggests a DC current through a coil of 250mA, and there are two coils, so 500mA.

Something like a StepStick oe EasyDriver board might work, but the low motor voltage may be a problem. Ratings for those boards seem to be 7/8 V minimum for motor supply, which may overheat the motors.

Otherwise use a basic H-Bridge that works at 3.3V or 5V.

Keep the supply to the motors separate to the Pi supply, at least by using separate regulators for each.

NB, if you want to minimise wiring you could use one GPIO to drive the direction input of all stepper drivers (of the direction and step two input type) Use one GPIO per motor for the step. Then 5 motors only takes 6 GPIO / 6 wires. Set direction for all then step just the one motor you want to move. This assumes you don't need to move several motors at once in different directions.

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