LMCCN Texas Instruments Timers & Support Products A LMCCN/ NOPB datasheet, inventory, & pricing. LMCCN. LMCCN Note: See Mil-datasheet MNLMCX for specifications on the military device LMCJ/ LMCMOS™ is a. Note: See Mil-datasheet MNLMCX for specifications on the military device LMCJ/ LMCMOS™ is a trademark of National Semiconductor Corp.
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Jun 23, 1. Jul 22, 10 0. Hi all, First up, my apologies for another thread as I can’t find a similar thread to tag onto I’m attempting to make up a circuit that will trigger a key press on a keyboard with the help of a solid state relay.
I’ve attached a schematic of the actual circuit below but without a few modifications that I’ll mention later. Essentially, I’m taking a keyboard PCB and attaching the corresponding contacts for the space bar to a solid state relay. I’m planning on having 2 relays in series – one will trigger and simulate the space bar being pressed, one relay will light up an LED and the other will simply just close an external circuit for external expansion one of these relays are a dual SPST relay hence 2 relays!
So far, after about 2 days trawling through both Google here for inspiration I’ve come up with the circuit below but with a few modifications. For R1 I’ve decided to use a variable resistor finding a I’ve lost track of what I’ve read where but I did read something about having a capacitor as a supply bypass due to spikes from the when it changes state.
As the power is being tapped off the USB port in parallel to the keyboard am I guessing correctly that it would be dahasheet good idea to include this bypass and, if so, what capacitor should I use?
Also, which type of capacitors should I be using for my project – tantalums, ceramic or electrolytic as I am a complete novice! Or will there be something I need to add such as a resistor to ensure the SSR does turn off?
I’m hoping I’ve included enough info here but if I’ve omitted anything let me know!!! Also, if there is an easier way to accomplish the same task please let me know I’m all ears!!!
Jun 23, 2. Mar 24, 21, 2, You gave a lot of info, but I have to admit I’m still confused, so break it down. How long to you want this timer to work in secondsand what are you using to trigger it a push button? Jun 23, 3. Hi Bill, thanks for the extremely quick reply!!
After re-reading my post it looks like I completely forgot to mention how I’m going to use the timer!!
I’m trying to get the output to go low for 3 to 10 seconds which I’m hoping can be tweaked by the potentiometer and then I’m aiming for dahasheet mS duration for when the output goes high I pulled this figure out of thin air as I’ve really no idea how long to make the simulated key press – it just seemed to fit! Once the circuit is powered it will then be left alone maybe for a couple of hours without datasheeet further intervention. The idea behind this circuit is to automatically cue slides for presentations.
Usually you would just set the slides to automatically advance and set them to loop.
So in a nutshell, my plan is to make this timer press the space mlc555cn at predetermined intervals Hopefully I haven’t made things more confusing than they were before!! There’s times when I just can’t quite explain things simply and something tells me this could be one of those times so apologies if that’s the case!!
Jun 23, 4. Dec 20, 10, 1, The Cmos has a very low output high current especially when its supply voltage is daasheet 5V. Its output high voltage is spec’d with an output current of only 2mA which might not be enough to turn on your solid state relay.
LMCCN Datasheet pdf – CMOS Timer – National Semiconductor
An xatasheet has an output high voltage spec’d with an output current of mA vatasheet its supply voltage is only 5V. The supply current spike from a Cmos operating at your low supply voltage is tiny compared to the up to mA supply current spike caused by an ordinary Jun 23, 5. I have to admit I did have a moment of horror when you mentioned the 2mA output current – I just checked the datasheet of the SSR and datashedt that the stated maximum forward current is 2mA I had originally thought it was 3mA hence my brief moment of panic!!!
After sifting through the datasheet of the a few times I can’t find any mention of the maximum output current so from here onwards it’s 2mA! Thanks again for taking your time to reply! Help with timer circuit please!
Posted by nodestination1 in forum: HELP with timer Posted by itel in forum: Help with making a timer circuit Posted by paulareno in forum: You May Also Like: Malware on Android Devices Mimics Hardware Specs and Wastes Billions of Dollars Ever wonder why so many Android apps ask users if they’d like to download obscure add ons like “smart charging”?
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