# Need Help: Controlling a Fan with a Time Delay Relay

#### Nicholas Shake

Joined Jun 3, 2015
8
Hi there.

I would like to start out by saying that I am very grateful for this forum and all the people here that are willing to take time out of their days to help others. I usually don't ask questions unless I've completely exhausted Google and tried to learn on my own how to solve my problem.

I have been searching for weeks and have been trying to learn the basics, but have fallen short. I have to get this done though. I need to solve this problem and then study and learn from it so that I can help others understand (I am a teacher who was forced to take over an “Electronic Circuits" class for the rest of this year). I could just ride out the year and let the kids use the time for a study period, but I'd rather try to learn and get to a point where I could teach these kids something. This project is in sync with our Horticultural Department (Aquaponics) and will ultimately be built (about 10 of them) and given to them to help keep costs down for their Aquaponics Project.

Now for my problem...

What I Need to Accomplish

I need to use a Time Delay Relay to control an 8” In-Line Duct Fan (with or without the Variable Speed Fan Controller).

By "control", I mean that I need the Time Delay Relay to turn the 8” In-Line Duct Fan On for 1-minute and then Off for 4-minutes.

Repeating this process over and over again (24-7).

Something that operates just like this without the day/night functions: https://www.hydrofarm.com/p/APCTART

What I Have to Work With

The In-Line Duct Fan:

Specs-
• Airflow - 720 CFM
• Dimension - 13" x 8.50"
• Duct Size - 8"
• Decibels - 76 (+/- 1.5)
• Speed Fan - 2860 RPM
• Power - 195W
• Input Voltage - AC 110V/120V 60HZ

SpecSheet PDF Not Available (I can scan the manual if needed)

The Time Delay Relay:

Specs-
• Product Name- Digital Time Relay
• Type- DH48S-S
• Contact Type- SPST
• Rated Voltage- AC 110V
• Frequency- 50/60 Hz
• Contact- AC 250V 5A Resistive Load
• Time Range- 0.1S-99H
• Mount Rail Type- 35mm DIN Rail
• Base Mount Hole Size- 4mm/0.16"
• Panel Size- 50 x 50mm/2" x 2"(L*W)
• Mounted Size- 45 x 45 x 94mm/1.8" x 1.8" x 3.7"(L*W*Depth)
• Total Size- 48.5 x 60 x 109mm/1.9" x 2.4" x 4.3"(L*W*H)
• Color- Beige, Black
• Net Weight- 202g
• Package Content- 1 x Digital Time Relay w Socket

Description-

Features a Clear Plastic Cover on the Panel, Power On Delay, One Group of Delay Contact.
• Power Delay Operate Mode
• Panel Mounting Type
• 8-Pin Terminals for Installation
• 4-Digits Display and Double Row Knob for Setting Time

SpecSheet PDF(s) attached (See PDF referenced with "(best)" first)

The Variable Speed Fan Controller:

Specs-
• Internal, Electronic Auto-Resetting Circuit Breaker
• State-of-the-Art Electronics
• Rated for 350 Watts Max
• 120VAC Voltage Capacity
• 1-Year Warranty
• Specifically made for use with fans and blowers
• Correctly Manipulates Input Power Sine Wave
• Stall Speed Range Eliminated to Eliminate Fan Stoppage
• Internal Self-Resetting Circuit Breaker in case of Over-Voltage

SpecSheet PDF attached

Notes

Please help me get this Time Delay Relay to control the 8” In-Line Duct Fan. The Variable Speed Fan Controller can be taken out of the equation if it poses any extra pains.

I would like to incorporate the Variable Speed Fan Controller (so we can save power), but I am happy and grateful to get any and all help.

Regards

Nicholas Shake

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#### GS3

Joined Sep 21, 2007
408
Wow, most people come here with some vague idea and no specific information. You definitely have done your homework. Bravo.

OK, you connect the fan to the variable speed control. No problem there at all.

Then comes the timer. If you want or have to to use that timer then fine but, really, if this is a setup that is not purely temporary and for very short time, you can use a tiny circuit that costs 1/100th of that timer and it will work forever. You can build your own or you can buy one. If you search ebay or banggood for *cycle timer* you can get a digital one for between $5 and$10 to which you will need to add a power supply and box.

It is most probably not worth your time or effort but if you want to build your own timer from scratch someone will be along shortly to discuss secret weapon 555.

In any case, this is very easy.

I am curious though that, having a speed control, you still want to cycle. Why the need? Why not just lower the speed?

#### TheButtonThief

Joined Feb 26, 2011
237
someone will be along shortly to discuss secret weapon 555.
Love it!

Hi Mr Shake

Is a programmable timed relay necessary? You mentioned that you want to cycle the fan on for 1 minute and off for 4, will that ever change? Also, what conditions would dictate the speed of the fan? Could that be automated? Since it's for an "electronics circuits" class, why not build a circuit that can cycle the fan and control it's speed? It'd be very simple and you'd do away with the expensive instrumentation that simply requires wiring together and isn't really an electronics exercise.

We'd gladly help you out with such a circuit. It's be really simple to design, though assembly may be a little more complicated but it's an electronics class after all, it's what they're their to learn.

#### Alec_t

Joined Sep 17, 2013
13,057
From my understanding of the Chinglish datasheet for the relay it would need additional timing circuitry to provide a 4-min repeat function. IMO you might as well make one circuit to provide both the repeat function and the 1-min timer function, thus avoiding the need for the relay. This is in line with what GS3 and TheButtonThief are suggesting. The 555 has been mentioned, but for time periods of 1 min or more it is rather marginal (because of uncertain capacitor leakage). A CD4020 or CD4060-based circuit would be relatively simple to build and could do the timing and speed control.

#### GS3

Joined Sep 21, 2007
408
The 555 has been mentioned, but for time periods of 1 min or more it is rather marginal (because of uncertain capacitor leakage).
I have used it successfully for timing of several minutes using low leakage tantalum capacitors. Not really a problem.

The more important aspect is if it requires a timing exact to the milisecond or if there is some latitude.

#### TheButtonThief

Joined Feb 26, 2011
237
The more important aspect is if it requires a timing exact to the milisecond
I often opt for a micro if timing in milliseconds is critical.

I'd imagine, for the purpose of this project and the purpose of educating school students, a circuit based on a 555 would be perfect. This is however, if the OP is cool with the concept. He may still want to use the parts he listed, perhaps they're parts that he already has.

#### AnalogKid

Joined Aug 1, 2013
10,113
An alternative approach would be a not-quite-so-low frequency 555 astable circuit (or a higher freq oscillator and divider like a 4060) followed by a 4017 with output 5 tied to reset. This way, any of the 4017 outputs 0-4 will be on 20% of the time, and can drive a $2 solid state relay. If using a 555, the timing cap will be 80% smaller than if it drives the fan power switch directly, always a good thing. Either way, I agree with the posts above - build the timer circuit, buy the power parts. ak And YES, great question skills! #### GS3 Joined Sep 21, 2007 408 The 555 has been mentioned, but for time periods of 1 min or more it is rather marginal (because of uncertain capacitor leakage). A CD4020 or CD4060-based circuit would be relatively simple to build and could do the timing and speed control. I had memories of having designed a 555 circuit with a period of several minutes but after fresh calculations I get resistor and capacitor values which are too high so I would probably go with the divider idea. A simple and expedient way of doing it is to divide the mains frequency. A lot depends on the precision required. #### AnalogKid Joined Aug 1, 2013 10,113 5 minutes would be an 18,000 count cycle. Not exactly binary-decoder friendly, but more accurate than a 4060. ak #### GS3 Joined Sep 21, 2007 408 About 2^14~15. Not too bad. #### AnalogKid Joined Aug 1, 2013 10,113 Here is a 555 based solution. The 4017 counter creates a 20% duty cycle, reducing the size of C1 by 80% (very large caps do not work well in timers). An alternate configuration replaces Q1 with Q2 and Q3, eliminates D1, and reduces C1 to 47 uF. Power can be any 5 V or 12 V wall wart or USB charger. Even at "only" 30 seconds I'm not wild about the long timer period. Last September I did a similar fan timer on another forum, based on the CD4060. I can modify and post it if interested. ak #### Attachments • 14.3 KB Views: 6 #### TheButtonThief Joined Feb 26, 2011 237 I think the OP's lost interest =( Thread Starter #### Nicholas Shake Joined Jun 3, 2015 8 Wow, most people come here with some vague idea and no specific information. You definitely have done your homework. Bravo. Thank you very much. I spent some time putting it together. I usually don't have such complicated problems (where I am 100% in the dark). But when I do need to ask people for help (and expect them to go out of their way to help me with something), I figure I should be as clear, respectful, thoughtful, thorough and courteous as possible. I want to make sure the OP is nice and sturdy so that it can be understood by anyone else who might have the same (or similar) question. OK, you connect the fan to the variable speed control. No problem there at all. Well that's a relief Then comes the timer. If you want or have to to use that timer then fine but, really, if this is a setup that is not purely temporary and for very short time, you can use a tiny circuit that costs 1/100th of that timer and it will work forever. You can build your own or you can buy one. If you search ebay or banggood for *cycle timer* you can get a digital one for between$5 and $10 to which you will need to add a power supply and box. I don't have to use this Timer. I would like to go the easier route. And because I don't have much knowledge in this field, I think learning from something a little more basic would ultimately be a better decision. Now I can look on eBay and find one of these "Cycle Timers", but there are so many choices (because I am not too sure about the power needs). As with the part I already have, there are Input needs, Output needs, AC in, DC in, AC out, DC out, etc... And choosing the right one would really be something I'd need some assistance with (Please). I bought this one because I wasn't sure what I needed, and I thought that (from the item’s description) that it would work. More of a guess with hopes. It was only$14, so I can just send it back or hold onto it for something else down the road.

But it would be nice to know how to use this specific Timer (the one I already have) as well because I can get these Timers even cheaper in bulk.

It is most probably not worth your time or effort but if you want to build your own timer from scratch someone will be along shortly to discuss secret weapon 555.

It's funny you mention the "555". The next lesson I am suppose to study up on is actually this same project with a "555". So I think that starting with the easier route first, and then expanding to a "555" would be great (as long as nobody objects to this).

The only thing I would want to know first (before getting into the "555") is about the other choices like the "555".

I saw this other Repeat Cycle Timer (http://www.canakit.com/1-minute-adjustable-on-off-cyclic-timer-kit-ck191m1-uk191m1.html) that used 2x 4541 Programmable Timer Integrated Circuits instead.

Would this 4541 be better for what I need?

I unfortunately cannot afford these DIY Kits, but something like them would be great.

I am curious though that, having a speed control, you still want to cycle. Why the need? Why not just lower the speed?

From what I understand, the fan doesn't need to use the speed control. But my colleague told me that in the winter they don't need to move as much air in those specific cycles. If using the Variable Speed Controller to lower the speed actually lowers the amount of electricity used when using the fan, then that would be a bonus.

For their project (my colleague's Aquaponics Project), they have to use the 1-minute On & 4-minute Off cycles no matter what (as per their curriculum). In the summer, the fan can be used at its normal speed. It can be ran like this in the winter too. But my colleague said that they have had better results using the fan with a speed Variable Speed Controller at lower speeds for that "1-minute On" cycle (in the winter). I believe it has to do with the new air coming in being cold, and the heater inside not having to work as hard (and maybe the Variable Speed Controller at a lower setting saving some electricity?). In the summer here, it's hot. And the fan running at full-throttle actually helps balance the temperature (by bringing in fresh cool air).

The Timers the School District initially bought for the Aquaponics Project were ready to go right out-of-the-box. They looked similar to the speed Controller in the OP (In regards to an outlet on the front and the plug for the wall on the back) without the knob. And I guess they had Timers in them with cycle presets of 1-minute On & 4-minutes Off. I was told that these Timers went straight into the wall, then the Variable Speed Controller plugged into the Timer, and then the fan plugged directly into Variable Speed Controller. The company who made this Timers went out of business after 10-20 years though, and the new options available to the District are not in their budget. So my boss got one of the teachers to build them in a class. Which then became part of the Electronic Circuits Class curriculum, and they've been doing it ever since. The teacher is now gone, and now I have to figure it out. But I felt a huge relief this morning when I woke to find notifications on my phone (for replied to this thread).

The Timers we had before (not actual Timer, but they look similar):

Thank you for ALL of your Replies. I am researching each Reply before I answer just to make sure I don't sound too Noob-ish or waste anyone's time.

Regards

Nicholas Shake

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#### Nicholas Shake

Joined Jun 3, 2015
8
I think the OP's lost interest =(

I am so sorry guys. We had our power out for a few days and the browser on my phone made it really difficult to use the forum.

Every year around our first snow, we have heavy power outages and we usually lose power for a few days. I live way up in in the Rockies by the Rio Grande in a very (VERY) rural area. I have to commute 1-1/2 hours (each way) everyday to get to work, I don't have any neighbors within a 10-mile radius, and the power up here is really dirty.

But everything is fine now and I have my new generator up and running. I hadn't hooked it up yet because I figured it wouldn't be needed for another couple of weeks.

I am really sorry if I made it seem as if I had lost interest. That is not the case at all. I still need to get this figured out and I hope that I haven't offended anyone by my brief absence.

It won't happen again.

Regards

Nicholas Shake

#### Nicholas Shake

Joined Jun 3, 2015
8
I often opt for a micro if timing in milliseconds is critical.

I'd imagine, for the purpose of this project and the purpose of educating school students, a circuit based on a 555 would be perfect. This is however, if the OP is cool with the concept. He may still want to use the parts he listed, perhaps they're parts that he already has.

Educating with the 555 sounds best. But I would really like to learn how to wire this Timer up as well. I was thinking about the options you had suggested and last night I thought about them all. There is a lot of great information about the 555's all over the internet, and if there are any that pertain to my situation specifically, I wouldn't want to take up anymore space (beating a dead horse).

I would like to learn how to use the 555 for this setup, and learn how to incorporate the Timer I already have if possible.

Since I already have this Timer in my possession, I'd like to learn how to wire it up and make it work for my situation. Then learn how to incorporate a 555 instead of this Timer.

Which do you think would be the easier way to go first?

Which one do you think I should start with (the Timer I already have, or the 555 route)?

Regards

Nicholas Shake

#### Alec_t

Joined Sep 17, 2013
13,057
The specs for the timer are somewhat confusing. There are several versions of the DH48S. Can you confirm that the one you have is the DH48S-S ? Only that version seems to be cyclic, with separate control of the ON and OFF periods.
I note that the contact rating is specified only for resistive loads (which a fan isn't), so I'd be concerned that using the timer to drive the fan directly might result in a short contact life. So use of the speed controller would be preferable, since the spec mentions that it is suitable for use with fans.

#### Nicholas Shake

Joined Jun 3, 2015
8
The specs for the timer are somewhat confusing. There are several versions of the DH48S. Can you confirm that the one you have is the DH48S-S ? Only that version seems to be cyclic, with separate control of the ON and OFF periods.
I note that the contact rating is specified only for resistive loads (which a fan isn't), so I'd be concerned that using the timer to drive the fan directly might result in a short contact life. So use of the speed controller would be preferable, since the spec mentions that it is suitable for use with fans.

It is For Sure the DH48S-S

Regards

Nicholas Shake

#### Alec_t

Joined Sep 17, 2013
13,057
In that case it looks as though you'd just plug the fan into the speed controller, plug the controller into a 3-receptacle socket, connect line and neutral to the timer's power input pins 2 and 7, connect line to pin 8, use pin 6 as a switched line to the line-in receptacle of the socket, and connect the other receptacles of the socket to neutral and earth respectively. I can't see from the pics and datasheets how you set separately the ON time and OFF time of the timer. There are 6 pairs of buttons. Is that 3 for the ON time and 3 for the OFF time?

#### Nicholas Shake

Joined Jun 3, 2015
8
In that case it looks as though you'd just plug the fan into the speed controller, plug the controller into a 3-receptacle socket, connect line and neutral to the timer's power input pins 2 and 7, connect line to pin 8, use pin 6 as a switched line to the line-in receptacle of the socket, and connect the other receptacles of the socket to neutral and earth respectively. I can't see from the pics and datasheets how you set separately the ON time and OFF time of the timer. There are 6 pairs of buttons. Is that 3 for the ON time and 3 for the OFF time?

Yes.

There are 3 pairs of buttons for the ON time and 3 pairs of buttons for the OFF time.

But, the First and Second buttons (in each of the two pairs of 3 buttons) are for Numerical Digits, and the Third button is for Switching Between Minutes and Seconds.

Could you possibly make a diagram for me and the thread?

Even if its just a sketch on a piece of paper that you took a photo of and uploaded.

It would make it easier for me to confirm what it is I am going to do (before doing it).

I don't want to take any chances with this type of electricity.

Thank you so much for taking the time to explain this.

Regards

Nicholas Shake

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#### Nicholas Shake

Joined Jun 3, 2015
8
An alternative approach would be a not-quite-so-low frequency 555 astable circuit (or a higher freq oscillator and divider like a 4060) followed by a 4017 with output 5 tied to reset. This way, any of the 4017 outputs 0-4 will be on 20% of the time, and can drive a \$2 solid state relay. If using a 555, the timing cap will be 80% smaller than if it drives the fan power switch directly, always a good thing. Either way, I agree with the posts above - build the timer circuit, buy the power parts.

ak

And YES, great question skills!

The timing doesn't need to be super accurate.

OFF for 240 Seconds (or 4 Minutes) could be between 200-300 Seconds. The OFF Cycle's accuracy isn't as important as the ON Cycle's accuracy.

ON for 60 Seconds (or 1 Minute) needs to be at least 60 Seconds. So anything between 60-90 Seconds would be fine.

I would like it to be as accurate as possible without costing too much extra and without it being twice as difficult.

If you could explain it so I could try and understand it (for someone who has no knowledge of anything in this area), that would be awesome. Afterwards, I'd like to turn it into a Step-By-Step Tutorial with Photos to share here.

Regards

Nicholas Shake