(Version 10 revised: 10 June 2020)
The following list is meant to be comprehensive, but is subject to change. All parts are commodity products and prices will vary greatly. The prices quoted below came from Walmart.com and eBay and are what I actually paid. Those from eBay are for small quantities with deliveries from the US. If thinking long term or larger quantities, prices drop significantly when purchased from China. Your mileage may vary up or down depending on how you source your parts and in what country you live. At the moment, I have not supplied explicit vendors for any of the parts. If InqVent were to go viral, vendors may offer us opportunities and this page will be updated accordingly. Here at the top, I go over the main components. At the bottom is a table repeating these main components along with parts costing less than $1 US in one accessible location.
Note about electronics – Many of the electronics were selected because they were already in my part bins. As I am not an Electrical Engineer, but what I would call a cook-book electronics guy, parts may change as people with more expertise make suggestions about improving the circuit.
INTEX Quick-Fill DC Electric Air Pump, 23.0CFM
- Quantity needed: 1
- Price paid: $5.30
This air-mattress pump was selected mainly for using 12 volts, and being inexpensive and compact. I validated the maximum pressure available on this and one other brand and found them both to be about the same at around 32 cm-H2O. I suspect any 12 volt air-mattress pump will have similar characteristics. Another major advantage – this model has a locking feature where as other units rely on friction to connect the blower unit to their nozzles. InqVent’s 3D printer models are modular and in this case, I have expectations that multiple interface adapters can be designed to take advantage of varying stock around the world. The electronics and software are tolerant to using various air pumps.
Generic Laptop AC Adapter
- Quantity needed: 1
- Price paid: $9.99
InqVent’s electronics and software are tolerant of a wide range of DC voltages from 12 volts up to 20 volts. The best selection will be with laptop power supplies in the 45 watt range. These often have the ability to use either 110 VAC or 240 VAC. The one I use in the prototype is a 19.5 volt, 2.3 amp version. Pick laptop power supplies that offer over-current protection which is necessary to protect itself from damage. The air pump above, if allowed to go full tilt can draw 100 watts. Fortunately, InqVent only needs a small percentage of the pump’s and this power supply’s rated power.
MG90S Micro Metal Gear 9g Servo
- Quantity needed: 2
- Price paid: 5pc for $13.95 =>$5.58
InqVent’s 3D Models are sized for this 9g servo. There is some tolerance for variability in sizes that I have found for these type servos. Make sure to get the metal gear versions. They are more durable, support higher speeds and torque than the plastic gear versions.
WeMos D1 Mini – ESP8266, ESP-12 Based Microprocessor
- Quantity needed: 1
- Price paid: $3.99
This is the main brain of InqVent. In the Arduino / Maker’s world, the ESP8266 is the rock star of microprocessors. It is small, inexpensive, powerful, and supports WiFi networking. It has enough power and memory space to host a web server, a sizable website and still have enough processing power left over to process sensor data, control motors and the AI calculations required for InqVent. This WeMos D1 Mini is a development version that adds UBS connectivity and power converters. Make sure you get a version that has the full complement of headers as illustrated. You’ll use two of the 3 sets supplied in an InqVent.
BMP280 – Pressure, Temperature Sensor
- Quantity needed: 2
- Price paid: 5pcs for $9.15 => $3.66
Version 8 and above of InqVent uses two BMP280 sensors with breakout board for measuring pressure. As a bonus, temperature is also available. If you choose, you can get the BME280 version that also supports humidity measurement. Research indicates temperature and humidity are useful pieces of information with regard to ventilation.
Mini360 3Amp DC Voltage Step Down Power Converter Buck Module – Variable output version.
- Quantity needed: 1
- Price paid: 10pcs for $6.95 => $0.70
This component takes a large voltage such as our 19 volts DC and converts it to a lower voltage. There are five versions. Four are fixed output voltages of 3.3, 5, 9 and 12 volts. The fifth has a configurable output voltage. We use this version as we need 6 volts to drive the servos.
RFP30N06LE Mosfet TO-220
- Quantity needed: 1
- Price paid: 10pcs for $10.40 => $1.04
TO-220 Heat Sink
- Quantity needed: 1
- Price paid: 10pcs for $6.99 => $0.70
ABS Plastic
- Quantity needed: ~250 gm
- Price paid: 10 rolls for $99 => $2.50
At the moment, I am specifying ABS as it is the material I use. However, it is more difficult to use and often needs an enclosed chamber. Not all printers can handle ABS. Also, the models have been tuned to account for ABS’s higher shrink rate. It will be a TODO item to explore alternative models for PLA.
Prototype Breadboards
- Quantity needed: ~4 sq-in (~2580 sq-mm)
- Price paid: Way less than $1
InqVent version 10 uses two boards with a total area of about 4 sq-in (2500 sq-mm).
O-Ring Gaskets – Metric size 1×17
- Quantity needed: 2
- Price paid: Way less than $1
Although metric, it was readily available at the local Walmart or home supply warehouse.
Full List
Here is the full list, including the described components above.
| Item | Quantity | Total Cost |
| INTEX Quick-Fill DC Electric Air Pump, 23.0CFM | 1 | $5.30 |
| Generic Laptop AC Adapter | 1 | $9.99 |
| MG90S Micro Metal Gear 9g Servo | 2 | $5.58 |
| WeMos D1 Mini – ESP8266, ESP-12 Based Microprocessor | 1 | $3.99 |
| BMP280 – Pressure, Temperature Sensor | 2 | $3.66 |
| Mini360 3Amp DC Voltage Step Down Power Converter Buck Module – Variable output version | 1 | $0.70 |
| RFP30N06LE Mosfet TO-220 | 1 | $1.04 |
| TO-220 Heat Sink | 1 | $0.70 |
| ABS 3D Printer Filament | ~250 gm | $2.50 |
| 1N4001 Diode | 1 | |
| O-Ring Gaskets – Metric size 1×17 | 2 | |
| 10kΩ Resistor | 1 | |
| 2-1/4″ Sheetrock Screws | 5 | |
| 470 μF 16 Volt Electrolytic Capacitor | 1 | |
| Circuit Board | 1 | |
| Rubber or Felt feet | 4 | |
| TOTAL | 1 InqVent | ~$40.00 |
Other Consumables
This list is probably not comprehensive, as I didn’t write down every item I used. If you are a Maker, then you already have these and know what you need.
- 24 gauge wire multi colored
- Solder
- Sandpaper 200 grit
- Acetone
- 2.25″ Sheetrock screws
Tools
Same thing for this list… certainly not comprehensive.
- 3D Printer
- Xacto knives
- Various screw drivers
- Solder iron
- Volt Meters