LED Scrolling Clock
Posted: Wed Dec 26, 2001 5:56 pm
In the article by Fred Blechman I have modified this great clock by upgrading the display to the Giant 4" high DOT Matrix Liteon
LTP 4157AC, a pin-for-pin replacement for the small LTP1157 provided by the kit maker. This requires slowing the scroll speed a bit. The display output is brilliant without modifying the circuit board (other than decreasing R1-R7 to 30 ohms)<p>My question is this:
I also have two other giant Liteon displays (also pin-for-pin replacements) which are less efficient and require a higher voltage to get a decent output (green LTP 4157AG and red LTP 4157 AHR). Even with reducing R1-R7 from 100 ohms to 5 ohms, these displays are hardly visible. It seems that these two other displays are less efficient and need 5v or better @ 60 ma. I know this since the dots can be driven by a 5-6 v battery with brilliant pulsed output. Is there any way of increasing the voltage/current to the above displays by modifying the circuit...e.g. using a higher voltage regulator or taking the 7 v off the main power to the ULN 2003As?[*]Scrolling LED Clock Further Modifications
LTP 4157AC, a pin-for-pin replacement for the small LTP1157 provided by the kit maker. This requires slowing the scroll speed a bit. The display output is brilliant without modifying the circuit board (other than decreasing R1-R7 to 30 ohms)<p>My question is this:
I also have two other giant Liteon displays (also pin-for-pin replacements) which are less efficient and require a higher voltage to get a decent output (green LTP 4157AG and red LTP 4157 AHR). Even with reducing R1-R7 from 100 ohms to 5 ohms, these displays are hardly visible. It seems that these two other displays are less efficient and need 5v or better @ 60 ma. I know this since the dots can be driven by a 5-6 v battery with brilliant pulsed output. Is there any way of increasing the voltage/current to the above displays by modifying the circuit...e.g. using a higher voltage regulator or taking the 7 v off the main power to the ULN 2003As?[*]Scrolling LED Clock Further Modifications