This kit allows you to illuminate the edge of a picture frame using a number of LEDs. This happens for a period of time when the button is pressed. The duration is set using a trimmer potentiometer and can be anything from a few seconds to 30 minutes. The student can choose which LEDs they would like to use. These are connected to the terminal block (along with a current limit resistor). The board can drive 200mA, which is about 10 high brightness LEDs.
This kit includes:
- 1 x PP3 Clip lead
- 1 x Battery holder (3x AA)
- 1 x Terminal block (2 way)
- 1 x Push to make switch
- 1 x Capacitor, electrolytic, 16V, 220uF
- 1 x 10M Pot
- 2 x 10K resistor 5%
- 2 x N channel FET (2N7000)
- 1 x 0.5 metre length of single core wire
- 1 x Picture frame LED driver PCB
PCB dimensions: 58mm x 28mm.
This kit is supplied as a pack of parts and requires soldering.
Selecting LEDs for using with the circuit.
The circuit can be used with a variety of LEDs. Below are a selection of LEDs that can be used. Also listed is the current limit resistor that will be required if four LEDS are used.
|3504 Standard red||33ohm|
|3505 Standard green||33ohm|
|3506 Standard yellow||33ohm|
|3542 Standard white||22ohm|
|3543 Standard blue||22ohm|
|3507 Ultra bright red||33ohm|
|3524 Ultra bright white||68ohm|
|3537 Ultra bright blue||68ohm|
Teachers can order a sample of this kit (one per school) here. You will need to select the kit from a list of all the sample kits; the stock code for this kit is 2146.
Note: this service is only offered to schools for evaluation purposes only.
This kit is designed and manufactured in the UK by Kitronik.
A video about our LED Picture Frame Kit taken from our Ask Kitronik Live event 2012.
A guide to understanding how a Potential Divider / Voltage Divider works. What is a Potential Divider / Voltage Divider? This is a simple circuit which takes advantage of the way voltages drop across resistors in series.
Is there a way to change the components on the board - say the capacitor, so that if 12V is used the discharge of the batteries is minimised without the use of the push button? The circuit works perfectly otherwise.
Posted byon Friday, 18 December 2015
As per your previous question this kit isn’t designed to run off 12V’s. The push button switch is only used to trigger the circuit, as there is no power switch on the circuit it is in a constant state of monitoring for the switch being pressed. If you want to conserve power you would need to add a power switch between the positive wire on the battery box and the positive input on the PCB.
Do you do this kit with a USB power version?
Posted byon Wednesday, 25 November 2015
We dont do this kit with a USB power lead, this is the only version we stock.
Is there any reason why the batteries would discharge over say a couple of months, when the push button has not been used? I am putting 12V through the board with no problems powering some bright LED's.
Posted byon Monday, 16 November 2015
Batteries will slowly discharge over time, also this circuit isn’t designed to work off 12V’s and as such there may be some current leaking through the circuit.
Can the 200mA output be increased? If so, how do you advise?
Posted byon Friday, 2 January 2015
You could use a different transistor with a higher current rating such as the BC337. This has a maximum continous current rating of 800mA. If you need more current than that you likely need a different circuit like a motor driver board or similar.
If you change the capacitor to 1000uF, would that then give the board more mA output current?
Posted byon Tuesday, 23 December 2014
The capacitor won’t have any impact on the output of the board, this will just increase the time of discharge and thus the LED’s will light for longer. The FET will determine the maximum output, in this case the maximum the FET and board can handle is 200mA.
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