20cm Display kit "Common Cathode"

To build-up large displays, leds seem to be the most inexpensive versus quality and this, in opposition to bulbs, plasma, TL tubes, etc... This kit contains a 7-segments display consisting of 12 leds per segment, respectively, and 4 leds for the decimal point. With the aid of a supplementary power supply with a little requirement, it is possible to connect this kit to any existing circuit equipped with simple common anode displays of any brand and any dimension. Just remove the small displays and connect the segments and anode of this 20cm display to the corresponding connections on the print. If the digit and segment drivers of the circuit can supply enough current it will be possible to connect in parallel two or more displays, or even, leave the small display of the circuit and to add the 20 cm display in parallel. This latter will not affect the brigthness of the 20 cm display due to the special concept of the driver's circuit (see further).

Specifications

• Common cathode
• Power supply : 22 to 26VDC non-stabilized
• Minimum cathode input voltage (off) : 2V
• Maximum cathode input voltage (on) : 1.5V
• Cathode input current (off) and (U = 5V) : 0.5mA
• Cathode input impedance : 10 K
• Segments input impedance : 10 K
• Segment minimum input voltage (on) : 1V
• Segment input voltage (off) : 0.5V
• Segment current : static (R6 = ~ ) : 40mA
  multiplex (R6 = 22 ohms) : 75mA
• Total absorbed current in static usage : maximum 400mA
• Maximum used power (U = 22V) : 8.8 Watt

Parts List

Label	Reference	Qty	Description
D1	1N4007	1	1N4007 DIODE 1A-1000V
D2	1N4148	16	1N4148 (1N914)
LD	LED5RL	90	LED 5mm RED 2.0 mcd TD UNIVERSAL
R1, R9	RA10K0	9	RESISTOR 1/4W 10K
R10	RA330E0	1	RESISTOR 1/4W 330E
R2, R8	RA33K0	10	RESISTOR 1/4W 33K
R4	RA1K8	1	RESISTOR 1/4W 1K8
R5	RA15E0	8	RESISTOR 1/4W 15E
R6	RA22E0	8	RESISTOR 1/4W 22E
R7	RA3K3	8	RESISTOR 1/4W 3K3
T1	2N1613	1	2N1613 SI-NPN AF 45V-0.8A- 60MHz
T2	BC237	9	BC237 SI NPN 50V 0.2A
T3	BC557B	8	BC557B SI-PNP UN 50V-0.2A
MANUAL	H2568	1	MANUAL 20cm DISPLAY COMMON CATHODE
COOLING	ML61	1	ML61 COOL.STAR TO5/TO39 15x15x9
PCB	P2568	1	PCB 20cm DISPLAY COMMON CATHODE