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John Wiltrout's Blog Power Straw
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  • Author Author: jw0752
  • Date Created: 31 Oct 2016 7:23 PM Date Created
  • Views 3246 views
  • Likes 9 likes
  • Comments 39 comments
  • medical devices
  • handicapped assist
Related
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Power Straw

jw0752
jw0752
31 Oct 2016

For several years my Mom has been in a Nursing Home with Parkinson's disease. As she has lost function of her muscles I have attempted to use technology to assist her. I have posted a couple of my attempts to assist her in my Blog on E-14.

 

https://www.element14.com/community/people/jw0752/blog/2015/07/07/hacking-a-lift-chair

 

https://www.element14.com/community/people/jw0752/blog/2016/01/15/building-an-led-amplifier-for-mom

 

Recently on her bad days she has been too weak to draw the thickened water she has to drink up a straw. This causes her to become dehydrated and quickly affects her health. She is very stubborn and will not allow herself to be fed by other than by herself. To help her in the days that she is too weak to drink through a straw  I have constructed this little device to assist her. I call it a Power Straw. It is very light on electronics so perhaps it does not have much application to our electronics site but since I had published previous projects I though a few of the guys would be interested.

 

Here is a schematic of the project:

 

image

 

I began the project by collecting a variety of potential components. My Goal was to draw her thickened water from a reservoir and pump it up a line and into her mouth. She is accustomed to using a push button call switch when she needs help from an attendant so I decided to use a very similar switch to actuate the pump.

 

The water line would run axially with the switch and its wiring. The switch could be held in her hand and the water feed line would continue past the switch by about 4 inches.

 

image

Picture of Hand Switch

 

I decided to try a small 12 volt water pump, that is usually used in small fountains, to pump the water from the reservoir.

 

image

Picture of Pump in the Reservoir

 

My first prototype did not include an in line solenoid. This created a problem if the cord accidentally fell to the floor as gravity would siphon the water from the reservoir and create a big mess on the floor. My final prototype needed a solenoid.

 

image

Solenoid Picture

 

Since space and weight were not a particular problem I decided to use two 6 volt 4.5 Ahr Lead Acid Gel Cells for the batteries.

 

image

Battery Picture

 

A small Volt Meter circuit was incorporated in the control box so I could check the level of the battery and recharge it when needed.

 

image

Control Box Picture

 

The control box is very simple with the Volt Meter and a momentary switch to activate it, a single P Channel MOSFET, Jacks for: Batteries, Charger, Pump, Solenoid, and actuation switch.

 

    imageimage

Pictures on inside the Control Box

 

The Reservoir is an lightly insulated hospital drinking cup that I brought home after a past overnight adventure.

 

image

Picture of the Reservoir.

 

Here is a picture of the finished project before I took it to Mom's room and nylon strapped it to the back of her wheel chair.

 

image

Picture of completed assembly

 

I can see room for many improvements. The parts that I ordered and received did not meet my imagined specifications. For example the pump could have a little more power and the solenoid draws too much current. While the batteries will be heavy enough to deal with the present solenoid, ideally, I should be able to find one that uses 200 mA or less instead of the current 400+ mA. I have made the reservoir and hand cord easy to disassemble for cleaning but improvements can be made. The plugs that were used on the pump and the solenoid were not polarized. While this will not affect the solenoid it is important the the pump spin in the correct direction for maximum efficiency. I have marked the non-polarized plugs but someone other than me might miss this detail. For the time being however Mom is happy and after the newness wears off she too will have some good suggestions for her sonny boy on how he can make it better.

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Top Comments

  • dougw
    dougw over 9 years ago +6
    They say need is the mother of invention, mothers are also the mothers of invention. Very nicely done John. If you are looking for improvement ideas, you might consider using a peristaltic pump - the liquid…
  • jw0752
    jw0752 over 9 years ago +6
    Here is the next iteration of the prototype using a peristaltic pump. The first thing to note is that the reservoir holder has been changed so that it will accommodate the standard drinking cup that is…
  • jw0752
    jw0752 over 9 years ago +5
    ERRATA : I have discovered that I made a mistake and published incorrect information reference the mA draw of the peristaltic pump. If one looks closely at the picture of the Fluke Meter in my last post…
Parents
  • jw0752
    jw0752 over 9 years ago

    I have begun the process to make improvements to the Power Straw. While I wait for the Peristaltic Pump, recommended by  dougw , which should arrive in two days, I have busied myself redesigning the control box. I want to control the dosing rate of the peristaltic pump so that the proper amount of water can be dispensed. Jan Cumps  had a good idea that I should use the LTC6992 voltage controlled PWM chip that I reviewed a couple weeks ago. I bread boarded this circuit last night and had it working very satisfactorily. Unfortunately the max voltage for the LTC6992 is 5.5 volts. Since I am running the Powered Straw from a 12 volt battery it was necessary to incorporate a 7805 regulator and related components. Here is what the LTC6992 circuit looked like.

     

    image

     

    To simplify I decided to go back to my old standard NE555 circuit driving an NTD4906 N Channel MOSFET. The 555 will run directly off the 12 volt battery which eliminates the need for a regulator and for this application I do not need the precision of the LTC6992. Here is a modified schematic for the Power Straw in this iteration and a picture of the completed and installed circuit upgrade to the control box.

     

    image

     

    image

     

    It is easy to see the simplicity and component reduction using the NE555 as opposed to the LTC6992. Here is a wider shot of the inside of the control box so that it can be compared with the pictures in the body of the blog.

     

    image

     

    I will post again when the Peristaltic Pump is installed and I am ready to give the unit another test run with Mom.

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  • jw0752
    jw0752 over 9 years ago

    I have begun the process to make improvements to the Power Straw. While I wait for the Peristaltic Pump, recommended by  dougw , which should arrive in two days, I have busied myself redesigning the control box. I want to control the dosing rate of the peristaltic pump so that the proper amount of water can be dispensed. Jan Cumps  had a good idea that I should use the LTC6992 voltage controlled PWM chip that I reviewed a couple weeks ago. I bread boarded this circuit last night and had it working very satisfactorily. Unfortunately the max voltage for the LTC6992 is 5.5 volts. Since I am running the Powered Straw from a 12 volt battery it was necessary to incorporate a 7805 regulator and related components. Here is what the LTC6992 circuit looked like.

     

    image

     

    To simplify I decided to go back to my old standard NE555 circuit driving an NTD4906 N Channel MOSFET. The 555 will run directly off the 12 volt battery which eliminates the need for a regulator and for this application I do not need the precision of the LTC6992. Here is a modified schematic for the Power Straw in this iteration and a picture of the completed and installed circuit upgrade to the control box.

     

    image

     

    image

     

    It is easy to see the simplicity and component reduction using the NE555 as opposed to the LTC6992. Here is a wider shot of the inside of the control box so that it can be compared with the pictures in the body of the blog.

     

    image

     

    I will post again when the Peristaltic Pump is installed and I am ready to give the unit another test run with Mom.

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