Just got a donation of nice part bins, been logging all parts in http://ecdb.net/login.php . Pain in the neck but it's got to be done, already I am able to find parts easier. 720 bins down and logged only 1000 left!
Friday, May 24, 2013
Congratulations on being slated to receive grant funding through the Vocational Equipment Grant program! This email provides logistical information about the event this coming Wednesday as well next steps in the contract process.
*Please remember that this information is embargoed and please do not share it outside of school administrators and program teachers.*
Vocational Equipment Grant Program
Massachusetts State House
Wednesday, May 29, 2013
The event will take place in room 157 of the Massachusetts State House. Enter through the “Hooker Entrance” at the front of the State House on Beacon St. After going through security, turn left. At the first bank of elevators, take a right and go down a very short flight of stairs. Room 157 will be on the right. Please give yourself a few extra minutes to go through security, especially as it is school group season here at the State House.
If you are taking public transportation, the State House is easily accessible by the Red or Green lines through the Park Street Station or the Orange line through the Downtown Crossing Station. The State House is a five minute walk up the hill.
If you are driving into the city, there are several parking garages located within a few blocks of the State House. A database of parking garages, locations, and rates is available at: http://boston.bestparking.com.
If possible, please email me to RSVP for this event with an estimated number of individuals who will be attending by Friday at 5:00PM. Please let me know if your school will not be represented at the event so that I can contact you by email or phone to discuss the contract process.
Contract Process Meeting
After the event, I will hold a short meeting for recipients to discuss the contract process.
Please do not hesitate to contact me should you have any additional questions. I hope to see you on Thursday, and I look forward to working with you!
Local Government Program Manager
Executive Office for Administration and Finance
State House Room 373
Boston, MA 02133
Follow us on Twitter: @MassANF
For information on the Community Innovation Challenge grant program, please visit the program website:
taxes-and-procurement/working- for-you/community-innovation- challenge-grant
To join the Community Innovation Challenge grant interest list, send an email to:join-fad-cicgrants@listserv.
Tuesday, May 14, 2013
Here is a design I made for a friend who wanted an white LED to turn on when it was dusk, but also wanted so adjustment via a pot. So off to pick a photocell, I picked a VT9ØN3 that was used in many low light applications.
Found this great app note at http://www.ladyada.net/media/sensors/APP_PhotocellIntroduction.pdf
turns out there are as couple of types of photocells the Ø material and the 3 material
Type Ø Material
This is a general purpose material. Its characteristics include a good temperature coefficient and fast response time, especially at very low light levels. Cells of this type have relatively low dark history. Type Ø material is often used in lighting controls such as nightlights, and security lighting
Type 3 Material
This is a high speed material with a spectral response closely approximating the human eye. This material is well suited for switching from one light level to another and offers our best temperature stability and response time. This material is often used in cameras and industrial controls.
Once ordered we tested the photocell characteristic curve and found the following:
Now the circuit we chose was a op-amp comparator type, this was a great circuit because we used a JFET input opamp the TL072 and current consumption was less than 1ma (our target current) and have a very crisp trigger level unlike using a single transistor or FET. We used a 25 turn precision pot to get the accuracy down to +/- 1 LUX at the set-point. In-fact a voltage of 1.625 at pin 3 (reference) was ideal for dusk at 7pm local, the photocell read about 130k ohms indoors at dusk shades open with 5.25 sqft total window area facing east+west (2.625 sqft ea) approximately 3 to 4 LUX
The protocircuit below:
Video of the circuit working:
And finally PCB