Skip to main content

So for the record, it was 26 calendar days to receive my timer modules from AliExpress (estimated delivery time was 30-50 days).

delay OFF timer 10s-24h 1843

And having been "burned" multiple times by these low-cost modules from Asia, let's be absolutely clear on what I am talking about.  Here's what the modules I received look like.  Note the "1843" marking on the right image of the circuit board.  Curiously, if you look at the online photos of some of the online listings, this marking is nowhere to be found.

But including shipping, these are essentially $1 DELAY OFF timer modules with a broad operating DC voltage range.

Here's my guess at the schematic.  Let me repeat myself.  This is just a guess!

delay off 1843 module guess at schematic

The real issue is how the "output" pin and polarity operates in terms of if/how it can be adapted to become a DELAY-ON timer module.  As Dusty observed, the behavior of the output pin of what is surely a custom-programmed microcontroller (uC) 14-pin chip is the key.  Since the transistor markings cannot be reverse-search to determine actual part numbers, I simply draw them as 3-terminal components.  I don't think it relevant to devolve into the nuances of whether these are BJT or FET devices.  If you even know what I'm talking about then good for you but again I don't think relevant to the matter at hand!

So here's the "thing."  When power is applied to the module there is a brief delay during which the module OUT pin (Output solder blob set to "-" level) is incorrect until the module uC "boots up" and properly sets its pin 1 to ON level.  Note that inverting transistor Q2 is between the uC output pin 1 and the module OUT pin; during the startup interval, the OUT pin is pulled to V+ by resistors R3+R6 or about 24K.

50msec flash

I can readily duplicate the brief flash when using the 10-cent 2N3904 inverter circuit previously discussed.  Here's a video of this brief flash followed by a 10 second delay then the 5V LED strip turning ON.  This interval appears to be about 0.05 sec...a scant 1/20th second but nevertheless enough to effect a "quick flash."  The goal is to eliminate the brief flash - hopefully the flash can be seen in the video:

Dusty, please confirm we are on the same page as it were.  I'm pretty sure I will be able to come up with an inexpensive modification that converts this to a DELAY-ON module that can drive either 5V or 12V LED strip sections and masks that brief start-up flash.

BTW, let me know what your parts "stash" looks like.  Do you have capacitors lying around?  Do you have an assortment of resistors lying around (or just 1K resistors)?  Etc. I have a rather large parts stash and if all you need are a few tiny parts that are less than 1/4" thick (per USPS rules), I will gladly send them to you with my compliments...or you can choose to send me 75 cents which I believe is the current cost of a non-machinable postage stamp...LOL.


Images (3)
  • delay OFF timer 10s-24h 1843
  • delay off 1843 module guess at schematic
  • 50msec flash
Last edited by stan2004
@stan2004 posted:

  Here's what the modules I received look like.  Note the "1843" marking on the right image of the circuit board.  Curiously, if you look at the online photos of some of the online listings, this marking is nowhere to be found.

Stan,  the modules I received do not have the 1843 marking either but they act exactly like the one in your video.

I don't really have a stash of parts.  A hundred 3904 transistors and 1k resistors. Fifty 1.1amp 30v poly switches.  Probably more than I will ever use but who knows.  Have enjoyed this process so far.  Sharing your parts is a very generous offer but I don’t mind adding to “my stash”  as I did order 20 of these modules.  If we get them to work great. If not, as you suggested,  up on eBay.

masking quick flash when converting delay off to delay on

Given your existing parts stash, above is what I deem to be the closest-exit. 

The external components are two (2) 2N3904 transistors which you have...and one (1) 47uF 16V capacitor.  These capacitors should be 5-cent parts but of course that's not the way the world works for the DIY hobbyist!  Note that an external resistor is NOT needed.

capacitor assortment for about 5 bucks

I found a capacitor assortment on both Amazon and eBay which apparently ships from within US for about $5 so about 5 cents per capacitor.  They appear to be the same assortment.

I tried to figure a method to modify the module itself but gets fairly tricky with tiny surface-mount parts.

I realize the external modifications sort of demotes the low-cost module concept.  And perhaps there is a true Delay-ON module out there for $1 that works out-of-the-box so to speak.  Note that the same external modification will work for 5V or 12V DC power ... of course you must attach an LED strip of the corresponding voltage!


Images (2)
  • masking quick flash when converting delay off to delay on
  • capacitor assortment for about 5 bucks

This is great.  The caps are on order. Should see them early next week.

I spent a lot of time looking for a cost effective delay on time module.  The closest I came to a solution was the delay on modules used for cars.  Problem was to change the delay required changing a cap.  Never could find a chart of caps and time delays.  With the solution you have come up with it will still be less than $1.50 each and changing the timing is a breeze with the dip switches.

So for now it is back to watching the mail box.  

I received the caps this week and was anxious to get one hooked up.  I had already put together a little wiring harness to plug into the timer module, power supply and the LEDs. I had planned to solder the cap to the module. I was ready and all I needed was the cap.

6B2D268A-F513-4BDF-814B-7854556A5158Everything worked as expected.  No flash, on after 10 seconds.  Wahoo. Hooked up a second one. Set it for 20 seconds.  Another wahoo!  

I then started to think about how to simplify and eliminate as much wire as possible.  Here is the final configuration I settled on.


One lead on each transistor was crimped directly into the connector. The leads that needed to connected together were folded to one side and soldered together.    The last two leads were folded in the other direction and a black wire added to connect to the LEDs.  Much simpler and more compact. If I was to order more modules I think I would get the ones without the connector and solder directly to the board.  That way it would lay flat.

Stan, I greatly appreciate you assistance in helping me with both your time and knowledge.  This is not something I would have ever been able to figure out myself.

I started this quest looking for a method of varying the on time of lights in my buildings.  I didn’t want to buy modules that I would need to learn to program.  Didn’t want to spend $10+ for each building. And I had hoped to find an out of the box solution.  While this isn’t an out of the box solution the journey to get here was a good one.  I enjoyed it. Learned a lot and am pleased with the final solution.  Changing the delay by dip switch is great.  Hopefully this weekend I will get the time to start putting these together.  


Images (3)
  • 6B2D268A-F513-4BDF-814B-7854556A5158
  • 2AF6AFB8-3074-4436-B36D-72C740A26577
  • 11A94961-85E3-43F8-9C17-212678F2D591

Add Reply

OGR Publishing, Inc., 1310 Eastside Centre Ct, Suite 6, Mountain Home, AR 72653
Link copied to your clipboard.