19hertz

ramblings of an electronic engineer.


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How Big is Space really?

Thought I’d share this interenting infographic on the size of space.

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Air Quality Monitor: Power Requirements

I have all but a few parts now for my air quality monitoring project so I decided to start working out I’m going to power it. Since I plan for this system to be portable I must choose a battery to power the system, but first I need to work out how much power is required during constant use. For a battery with a given voltage the amount of power is given by the number of milliamp hours (mAh) the battery has. Essentially it’s a value that you can use to determine the amount of time the battery will provide power at a given milliamp load.

For example if i had a battery with a 1000mAh rating it could draw 1000mA for an hour or 500mA for 2 hours or 10 mA for 10 hours etc…

If you know the amount of current you want to draw and the amount of time you want to power your device for you can work out the mAh ration you require. This is what I plan to do. There are other factors to choosing a battery (specific energy, cell voltage, c rating etc..) however I’m not going to get into them right not.

So here are my loads:

  • Temperature/Humidity Sensor: 0.12mA
  • LCD Display: 20mA
  • GPS: 25mA
  • General Air Quality Sensor: 120mA
  • Dust Sensor: 70mA
  • Carbon Dioxide Sensor: (has not arrived)
  • Ozone Sensor: (has not arrived)

Adding up all the loads together and taking a guess (120mA each) for the two sensors that haven’t yet arrives it looks like I’m going to need about 500mA or 0.5A to run the air quality monitor. One of the specifications it to be able to have operation of the device for around 8 hours therefor it looks like I’ll need a battery with a capacity of 4000mAh or more. There are other factors to choosing a battery (specific energy, cell voltage, c rating etc..) which I’ll need to consider before choosing a battery but for a initial look i’m thinking a battery design to recharge tablets may work quite well, this option would also mean I wouldn’t have to design any charging and discharging control gear. I’ll probably hold off on buying the battery for a while though until all the parts have come in and I have a prototype running, until them I can power everything from my benchtop power supply.


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New Year Resolutions

It’s probably a bit late for this but I thought I’d share my new years resolutions for this year. here they are.

  • Eat more healthily 
  • Read though the whole Bible again
  • Do something creative each week (photography/timelape, wood working etc..)

I am also going to try an Idea I mentioned before from the internet. Below is a list of 52 things I’d like to do over the year. Each week I am going to pick a random one and do it. So I didn’t have to write each on on individual card I’m using a deck of cards and have mapped each to a card i.e. 1 to 13 = 2♥ to A♥, 14 to 26 = 2♣ to A♣, 27 to 39 = 2♦ to A♦ and finally 40 to 52 = 2♠ to A♠. If you like any of these ideas in particular feel free to go try them 🙂

1. Watch clouds go by
2. Give blood
3. Update my top 10 online accounts with more secure passwords.
4. Finish reading a book
5. Climb a tree.
6. Take an I.Q. test.
7. Update my “bucket list.”
8. Build something out of wood.
9. Create a budget
10. Go for a bike ride to bureigh
11. Clean my room
12. Finish an electronic project
13. Learn to make a wrap
14. Do a time lapse
15. Blow bubbles and photograph
16. Play an instrument
17. Play a board game
18. Cook an apple pie
19. Organise my files
20. Write a extra blog post
21. Design am Eco house
22. Go lightpainting
23. Go for a random drive
24. Buy something using a drive through
25. Bake chocolate brownies
26. Clean up someone else’s rubbish
27. Watch a mid- night movie release
28. Look at pond water under microscope
29. Go see some glow worms
30. Launch a water rocket
31. Climb a mountain
32. Make some origami
33. Diet coke and mentos
33. Wash, vacum and fill up tyres of car
34. Go fishing off a pier
35. Feed ducks at a local park
36. Go on a picnic
37. Invite someone to go geochaching
38. Make an infographic
39. Plant a herb/veggie patch
40. Look up lyrics to songs
41. Make a sundial
42. Make homemade ice cream
43. Learn how to make lychee iced tea
44. Go have a coffee
45. Spend time with a friend
46. Write a script for a short film
47. Go for a run at the beach
48. Take a photo of legos
49. Rent and watch a movie
50. Make a recipe book
51. Cook my family breakfast
52. Go for a swim


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Happy New Year!!


Another year had come on gone and now is the time people stop to think about what they’d like to change in the coming year aka new year resolutions. And there is lot of ideas for things to change, some photographers will take this time to commit to a 365 day (photo a day) challenge or 52 week (photo a week) challenge while others have decided to have a resolution a week (an idea I’m thinking of adopting).

To aid those of you thinking about new years resolutions I want to share two blog posts which I found particularly useful. Firstly is a article by the gospel coalition on how to make your resolutions stick. I think it is particularly helpful pointing out that we should be looking to the reasons behind our resolutions and making them the motivation for going on. Also making yourself accountable to other with you resolutions was another idea that I appreciated.

The second link is for those whom have the resolution of reading through their bible in a year. Last year I finished reading though mine chronologically and it was hand down the best thing I did all year. There are various reading plans that you can get to aid you in this but I thought I’d share the one I’m going to use. It’s called the Bible Eater and is put out be the gospel coalition again.

Here’s how the Bible Eater works:

  • Old Testament: Read 2 to 3 chapters per day and take 4 days off per month. Read 1 to 3 designated one-sitting Old Testament books each quarter.
  • New Testament: Read 1 chapter per day and take 4 days off per month. One gospel is assigned to each quarter and Romans and Hebrews are assigned twice across the year.

If you plan on doing this I hope the format works well for you and wish you all the best.

As far as blogging goes, I’m still working on a few projects (albeit waiting for parts to arrive) and look forward to blogging for another year.

Happy New Year,

-David