Q: Increase transmit power/range

[denniskarlsson]

If I want to be able to send the signal to my entire house, how do I build such a thing?

[Mercoory]

I recommend you to check out Andreas Spiess's video based on @hzeller 's work : https://youtu.be/6SHGAEhnsYk

[denniskarlsson]

Yes, that's more like it, but it seems like the range still is very limited. According to the video it's just a few centimeters.

[hzeller]

Few centimeters is what the simple wire already provides, so the ferrite will possibly better.

I strongly suggest to ask some local ham radio person to help you with that. They know what can be done technically while still staying within legal limits.

[denniskarlsson]

ok, thank you. I will see what I can up with. I live far from anyone else so it shouldn't be a problem with a little more power on the transmitter.

[Mercoory]

In the video Andreas shows a circuit. And says the voltage for the amp circuit is set for his country's law ( Switzerland ). So check your country's regulation, and calculate with a formula the allowed voltage on that simple circuit.

[electrogoodie]

You circle the whole periphery of your house with four loops of solid wire like AWG14 (just look at the VLF antenna in airports) or follow Andreas Spiess's video on youtube on how to tune your humungous antenna for proper transmission line impedance matching or resonance

[pierow2k]

As @Mercoory mentioned earlier, Andreas Spiess makes a reference to Vcc at about 9:52 in the Remote Controller for Clocks video:

Please do not increase the supply voltage of the transistor to more than 3.3 volts as this will increase the transmitted power and therefore the reach of the signal.

[smeisner]

If anyone is interested, I created a PCB for the circuit above and will be receiving them in ~ a week (although with COVID-19, it may be held up at US Customs). The minimum order was 5, so I may have a few left over if anyone wants one. I made the board the same size as a Raspberry Pi Zero.

Top of PCB being made: https://www.meisners.net/images/wwvb-pcb.jpg

My plan is to solder a ferrite core antenna to the L1 pads.

Steve

[LIBHUT]

I'd be really interested in one of your PCB's -in need of another project for my lockdown!

[privatesam]

Hi @smeisner the comment from LIBHUT was me on my work account by accident. I would be very interested in one of the PCB's if we can arrange?

[smeisner]

Hi! Thanks for the second email. I meant to reply to your first post, but completely forgot. Sorry about that.

What is your shipping address?

I have 1 left, so it's yours!

Steve

On Mon, May 4, 2020 at 11:39 AM privatesam notifications@github.com wrote:

Hi @smeisner https://github.com/smeisner the comment from LIBHUT was me on my work account by accident. I would be very interested in one of the PCB's if we can arrange?

— You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub https://github.com/hzeller/txtempus/issues/8#issuecomment-623539201, or unsubscribe https://github.com/notifications/unsubscribe-auth/ABVHM3B2SNO7KYOPLJCFNSLRP3OTBANCNFSM4JGIRRMA .

[privatesam]

Hi Steve - thanks for this. Let me know your paypal so I can drop you some money for this. Just realised you're in the US and I'm in the UK so if its too much hassle no problem but my address is:

Sam Manley 5 Perceval Avenue London NW3 4PY

Thanks.

[smeisner]

@privatesam I put the envelope with a board in the mail today. I missed the postal pick up, so it will start moving tomorrow.

If you want to email directly, feel free to send me an email by going to my web site and using the email form:

https://www.meisners.net (use the "Email me" link at the bottom)

Steve

[privatesam]

@smeisner Thank so much! That is so amazing of you to go to the trouble. Will drop you an email now.

[GOTO-GOSUB]

I have also made some PCB's for this application. Please check my Github for more details.

A big thank you to Henner for his work on this excellent solution to a problem.

[harlock974]

Beware of typos in the above schematic. Component values should be :

R3 : 4.7 kΩ R2 : 560 Ω R4 : 200 Ω C1 : 1 nF L1 : 4.5 mH

L1 is Andreas' ferrite antenna inductance. C1 have to be calculated from L1 and from the requested frequency (40, 60 or 77.5 kHz) with the following formula :

C = 1 / (4×π²×L×f²)

[smeisner]

Beware of typos in the above schematic. Component values should be :

R3 : 4.7 kΩ R2 : 560 Ω R4 : 200 Ω C1 : 1 nF L1 : 4.5 mH

L1 is Andreas' ferrite antenna inductance. C1 have to be calculated from L1 and from the requested frequency (40, 60 or 77.5 kHz) with the following formula :

C = 1 / (2×π²×L×f²)

Thanks so much for the corrected details! I will give this a try at some point soon.

[smeisner]

Using the values in the schematic (as an example) and assuming freq of 60Hz and the units for L are in H, C is farad), I get:

C = 1 / (2 π² L 60²) C = 1 / (19.739208802 3600 L) C = 1 / (71061.151687843 L) if L = 1 nH (0.000000001 H), C = 1 / 71061.151687843 * 0.000000001 C = 14072 F That would be a huge value! Obviously I am doing this wrong.

[harlock974]

We both made mistakes. The formula is C = 1 / (4×π²×L×f²) (and not 1/(2×π²×L×f²) , I edited my last post). And I suppose your frequency is 60 kHz (60000 Hz). So you should use a capacitor of 7036 µF. Still quite large...

[smeisner]

We both made mistakes. The formula is C = 1 / (4×π²×L×f²) (and not 1/(2×π²×L×f²) , I edited my last post). And I suppose your frequency is 60 kHz (60000 Hz). So you should use a capacitor of 7036 µF. Still quite large...

Yes, sorry. 60kHz here in the 'states'.

That seems wrong....could it really call for such a large cap? I don't know enough about generating radio signals to really judge that.

[harlock974]

That seems wrong....could it really call for such a large cap? I don't know enough about generating radio signals to really judge that.

May be the inductance of your antenna is too low. As a comparison I can give you the values for the antennas I successfully used and the theoretical values of C for 60kHz :

• AM Loop antenna : 27 µH / 261 nF
• Ferrite antenna from an old AM receiver : 504 µH / 14 nF
• Inductor coil : 0.1H / 70 pF

The ferrite antenna give the best results with the longest range.

[jrotaetxe]

@smeisner

If anyone is interested, I created a PCB for the circuit above and will be receiving them in ~ a week (although with COVID-19, it may be held up at US Customs). The minimum order was 5, so I may have a few left over if anyone wants one. I made the board the same size as a Raspberry Pi Zero.

Top of PCB being made: https://www.meisners.net/images/wwvb-pcb.jpg

My plan is to solder a ferrite core antenna to the L1 pads.

Steve

Hi, Steve. Sorry for disturb you after so long, but I wonder if you still have docs to let me order somewhere a PCB to make the antenna circuit. Best regards Jon Rotaetxe

[smeisner]

I do have a Kicad 6 project. But so far, I can only find a newer version I made. Do you want this?

Feel free to email me directly at: steve at meisners dot net

Having direct access will be easier to share files.

Edit: @jrotaetxe ... sorry I didn't tag you in my reply

[nickapos]

For anyone who wants to calculate the components they can use this https://www.omnicalculator.com/physics/resonant-frequency-lc

[smeisner]

Looking at the second circuit described in #34 it looks like achive many meters of range is possible.

I'd be willing to make a handful of these (as SMD designs) populating everything (the N- and P-MOSFETs, the 10ohm and 100mF (that is 100 millifarad, right @harlock974 ?). The antenna and corresponding cap will be left off as it would potentially be different for everyone.

I could even make the cap & antenna pads thru holes to make it easy to populate. ...or I could make the very large SMD. And again, same form factor to fit the RPi Zero.

If I get enough interest, I will make a batch. Let me know by replying to me at: txtempus@meisners.net

BTW, thank you @nickapos for that link. Very helpful!!!

[harlock974]

I'd be willing to make a handful of these (as SMD designs) populating everything (the N- and P-MOSFETs, the 10ohm and 100mF (that is 100 millifarad, right @harlock974 ?).

No it is 100 nanoFarad. Sorry my handwriting is very poor (I edited #34 it is clearer now).

[smeisner]

ok, I have created the initial schematic & pcb in Kicad and have the files up for review: https://www.meisners.net/files/txtempus-sch.png https://www.meisners.net/files/txtempus-pcb.pdf https://www.meisners.net/files/txtempus-3d.jpg

C1 & C2 are user supplied and can be thru hole or SMD. The idea being the end user adds one of these caps. L1 is the antenna. Everything else will be populated.

The two MOSFETs were changed to AO3400A (N-channel) & AO3401A (P-channel) as the PCBS house has these on hand.

@harlock974 Can you verify these parts are OK as substitutions? Also, the orientation of Q1? It doesn't quite match your drawing. Here's the datasheets: https://datasheet.lcsc.com/lcsc/1811081213_Alpha---Omega-Semicon-AO3400A_C20917.pdf https://datasheet.lcsc.com/lcsc/1810171817_Alpha---Omega-Semicon-AO3401A_C15127.pdf

If anyone has feedback for the design, please let me know. I included 2 holes to be able to tie wrap a ferrite core antenna down.

So far, I have interest from @jrotaetxe and @nickapos ... anyone else?

FYI: I will charge actual cost for manufacturing and shipping to your location...that's all. The PCBs cost ~$2 USD for 5, so if I get 10 with assembly, it will be cheap per board. Shipping to US is ~$25.

[smeisner]

Well, that was quick. I already discovered a problem; Kicad has the wrong footprint for the 40 pin header. The orientation is off 180 degrees. I will fix this and repost later today.

[nickapos]

Hi Steve is the 2$ for 5 boards with the assembly including the various components?Can you also please let me know what is the shipping cost to the UK?Thanks and regards --------------------------------------------- Nick Apostolakis, MM0NKKOn 30 Oct 2023, at 18:10, Steve Meisner @.***> wrote: ok, I have created the initial schematic & pcb in Kicad and have the files up for review: https://www.meisners.net/files/txtempus-sch.png https://www.meisners.net/files/txtempus-pcb.pdf https://www.meisners.net/files/txtempus-3d.jpg C1 & C2 are user supplied and can be thru hole or SMD. The idea being the end user adds one of these caps. L1 is the antenna. Everything else will be populated. The two MOSFETs were changed to AO3400A (N-channel) & AO3401A (P-channel) as the PCBS house has these on hand. @harlock974 Can you verify these parts are OK as substitutions? Also, the orientation of Q1? It doesn't quite match your drawing. Here's the datasheets: https://datasheet.lcsc.com/lcsc/1811081213_Alpha---Omega-Semicon-AO3400A_C20917.pdf https://datasheet.lcsc.com/lcsc/1810171817_Alpha---Omega-Semicon-AO3401A_C15127.pdf If anyone has feedback for the design, please let me know. I included 2 holes to be able to tie wrap a ferrite core antenna down. So far, I have interest from @jrotaetxe and @nickapos ... anyone else? FYI: I will charge actual cost for manufacturing and shipping to your location...that's all. The PCBs cost ~$2 USD for 5, so if I get 10 with assembly, it will be cheap per board. Shipping to US is ~$25.

—Reply to this email directly, view it on GitHub, or unsubscribe.You are receiving this because you were mentioned.Message ID: @.***>

[smeisner]

@nickapos I want to get an idea of how many to order first. That will determine overall pricing. Once I get a solid count, I can create an estimate. I will be ordering 3 or 4 just for myself.

[denniskarlsson]

I'm interested in a PCB. Located in Sweden. What range will you be able to gain with this board?

[jrotaetxe]

ok, I have created the initial schematic & pcb in Kicad and have the files up for review: https://www.meisners.net/files/txtempus-sch.png https://www.meisners.net/files/txtempus-pcb.pdf https://www.meisners.net/files/txtempus-3d.jpg

C1 & C2 are user supplied and can be thru hole or SMD. The idea being the end user adds one of these caps. L1 is the antenna. Everything else will be populated.

The two MOSFETs were changed to AO3400A (N-channel) & AO3401A (P-channel) as the PCBS house has these on hand.

@harlock974 Can you verify these parts are OK as substitutions? Also, the orientation of Q1? It doesn't quite match your drawing. Here's the datasheets: https://datasheet.lcsc.com/lcsc/1811081213_Alpha---Omega-Semicon-AO3400A_C20917.pdf https://datasheet.lcsc.com/lcsc/1810171817_Alpha---Omega-Semicon-AO3401A_C15127.pdf

If anyone has feedback for the design, please let me know. I included 2 holes to be able to tie wrap a ferrite core antenna down.

So far, I have interest from @jrotaetxe and @nickapos ... anyone else?

FYI: I will charge actual cost for manufacturing and shipping to your location...that's all. The PCBs cost ~$2 USD for 5, so if I get 10 with assembly, it will be cheap per board. Shipping to US is ~$25.

The shipping to Spain (seems there is more interest in this side of the pond...). Also, a question... C1/C2 and L1 are to be chosen to resonate at the chosen frequency as they were a simple LC circuit? C1 and C2 are to be added aritmetically, or is the set C3+C1+C2 which is to be resonant to L1?

[nickapos]

If the total manufacturing cost is $2 for 5 boards, I will have 5. I don’t need 5 but that will make ordering easier. I will most likely use 2.Thanks and regards --------------------------------------------- Nick Apostolakis, MM0NKKOn 30 Oct 2023, at 18:29, Steve Meisner @.***> wrote: @nickapos I want to get an idea of how many to order first. That will determine overall pricing. Once I get a solid count, I can create an estimate. I will be ordering 3 or 4 just for myself.

—Reply to this email directly, view it on GitHub, or unsubscribe.You are receiving this because you were mentioned.Message ID: @.***>

[smeisner]

ok, I have created the initial schematic & pcb in Kicad and have the files up for review: https://www.meisners.net/files/txtempus-sch.png https://www.meisners.net/files/txtempus-pcb.pdf https://www.meisners.net/files/txtempus-3d.jpg C1 & C2 are user supplied and can be thru hole or SMD. The idea being the end user adds one of these caps. L1 is the antenna. Everything else will be populated. The two MOSFETs were changed to AO3400A (N-channel) & AO3401A (P-channel) as the PCBS house has these on hand. @harlock974 Can you verify these parts are OK as substitutions? Also, the orientation of Q1? It doesn't quite match your drawing. Here's the datasheets: https://datasheet.lcsc.com/lcsc/1811081213_Alpha---Omega-Semicon-AO3400A_C20917.pdf https://datasheet.lcsc.com/lcsc/1810171817_Alpha---Omega-Semicon-AO3401A_C15127.pdf If anyone has feedback for the design, please let me know. I included 2 holes to be able to tie wrap a ferrite core antenna down. So far, I have interest from @jrotaetxe and @nickapos ... anyone else? FYI: I will charge actual cost for manufacturing and shipping to your location...that's all. The PCBs cost ~$2 USD for 5, so if I get 10 with assembly, it will be cheap per board. Shipping to US is ~$25.

The shipping to Spain (seems there is more interest in this side of the pond...). Also, a question... C1/C2 and L1 are to be chosen to resonate at the chosen frequency as they were a simple LC circuit?

Yes.

C1 and C2 are to be added aritmetically, or is the set C3+C1+C2 which is to be resonant to L1?

The idea is the user is to populate C1 OR C2 ... not both. This will give the option to use THT or SMD. C3 will be on the board already.

[jrotaetxe]

.. and just a suggestion. Mount all the componets and some jumpers to fit DCF77/NIST frequencies. I feel it will increase the ineterested universe. A couple of SMD ferrite coils and capacitors could ease the whole for everybody and broaden the "market targetted" But 120% grateful with the proposal as it is.

[smeisner]

Ahh! This is why I posted the design; to get ideas!!

I don't know enough about RF and was worried adding jumpers could cause problems. But I suppose at this low frequency it wouldn't?

When you suggest adding ferrite coils, where are you thinking? Instead of the antenna?

If you want to suggest values to use, I will certainly add them and jumpers to select the freq.

[smeisner]

OK, I just got a quote for (10) boards for $16.11, plus shipping to me $17.46. Grand Total: $33.57 or $3.36 each ... plus actual shipping to your location.

The price will change if I do what @jrotaetxe suggested. But I doubt it'd be much more.

[nickapos]

The ferrite coil with the capacitor is a tuned circuit that is effectively the antenna.By changing the values if these two you can select frequencies. If you design it with jumpers, you can have two tuned circuits one for 60KHz and one for 77.5 and use them for MSF, WWVB or DCF77The values can be calculated with the online app I pasted. I don’t think there is going to be any interference by the jumpersThanks and regards --------------------------------------------- Nick Apostolakis, MM0NKKOn 30 Oct 2023, at 18:55, Steve Meisner @.***> wrote: Ahh! This is why I posted the design; to get ideas!! I don't know enough about RF and was worried adding jumpers could cause problems. But I suppose at this low frequency it wouldn't? When you suggest adding ferrite coils, where are you thinking? Instead of the antenna? If you want to suggest values to use, I will certainly add them and jumpers to select the freq.

—Reply to this email directly, view it on GitHub, or unsubscribe.You are receiving this because you were mentioned.Message ID: @.***>

[jrotaetxe]

For example, thils is a 470 uH that could play L1. https://www.coilmaster.com.tw/es/product/RCB0808471KLF.html For this one, a 15 nF capacitor would make the deal for 60 kHz and 9 nF would make the deal for 77.5 kHz. So a simple jumperr connecting either 9nF or 15nF capacitor to the proposed ferrite coil would cover both sides of the pond. Please, correct me if mistaken...

[jrotaetxe]

To achieve 9 nF, I would put a couple of 10 nF and 100 nF in paralel. This arrangement makes a total of the required 9 nF for a coil of 470 uH. For the 60 kHz model, a 15 nF is a normalised capacitance, so it can be achieved with a single cap. Summarizing. A 470 uH coil connected either to a 15 nF cap or to an array of Two caps in paralel, one of 10 nF and the other of 100 nF

[nickapos]

This is a great and elegant solution. I suspect the watches are doing something similar internally to cover multiple bandsOn 31 Oct 2023, at 07:49, jrotaetxe @.***> wrote: To achieve 9 nF, I would put a couple of 10 nF and 100 nF in paralel. This arrangement makes a total of the required 9 nF for a coil of 470 uH. For the 60 kHz model, a 15 nF is a normalised capacitance, so it can be achieved with a single cap. Summarizing. A 470 uH coil connected either to a 15 nF cap or to an array of Two caps in paralel, one of 10 nF and the other of 100 nF

—Reply to this email directly, view it on GitHub, or unsubscribe.You are receiving this because you were mentioned.Message ID: @.***>

[harlock974]

• The replacement mosfets seem fine.
• The 100nF capacitor is optional. It helps to remove some bumps in the signal when the inductance and the other capacitor are not perfectly matched.
• The max range is 10 meters with a direct line of sight and a Casio watch.
• Beware that this circuit works only with txtempus modified to remove attenuation pin usage. See my post in #34. Alternatively you can use time-signal.

[jrotaetxe]

• The replacement mosfets seem fine.
• The 100nF capacitor is optional. It helps to remove some bumps in the signal when the inductance and the other capacitor are not perfectly matched.
• The max range is 10 meters with a direct line of sight and a Casio watch.
• Beware that this circuit works only with txtempus modified to remove attenuation pin usage. See my post in [Suggestion] Removal of attenuation pin #34. Alternatively you can use time-signal.

Hi, Harlock. What I cannot catch from your sugeestion is that with your proposed values (22 nF and 700 uH) the calculated resonance value is 45 kHz more or less, far from the 60 kHz required... This is driving me nuts....

[jrotaetxe]

Catched the Fish!!!. You are using Japanese signals, (JJY40) that are emmited at 40 kHz!!!!.

[harlock974]

Catched the Fish!!!. You are using Japanese signals, (JJY40) that are emmited at 40 kHz!!!!.

Exactly !!!

[jrotaetxe]

Then the path to follow is clear (in my oppinion. Mount the 470 uH coil and leave pads to mount two capacitors in paralel. For Europeans, we have to mount two caps, 100 nF and 10 nF, 4.7 nF each USA citicens, one of 15 nF Japanese, two same caps of 15 nF each. in paralel (like Europeans, but with USA oriented caps)...

[jrotaetxe]

Something wrong with my calculations...

So summarizing the summary:

I would put the 470 uH coil already suggested and leave pads to solder two capacitors in paralel.

USA: Only one capacitor, 15 nF JAPAN: Two capacitors, 15 nF, in paralel EUR: Or one cap of 10 nF or a couple of 4.7 nF in paralel

Depending on the results, perhaps we have to cut the track of the 100 nF cap. For lower capacitances can be disrupting when tunning to higher freqs (EUR, perhaps USA)

[smeisner]

ok, files updated on my web server to match jrotaetxe's summary. I made the footprints for the C1 & C2 caps large (1206 / 3216Metric) to make them easier to solder.

After updating the design (based on @jrotaetxe 's feedback & ideas), I created another quote for 15 units. It comes out to $47.70. So still ~$3 per board. This includes Q1, Q2, R1, C3 and L1 already soldered. If people want, I will solder C1 & C2 on as well prior to sending them out. ...no additional cost. They are cheap and it's easy.

So we're looking at slightly more than actual shipping to your location.

Please take a look at the design files and I can submit the order if no more ideas or requests. Please give a "+1" here to confirm.

[smeisner]

@harlock974 for the inductor I chose, the DC Resistance is 40Ω. Should R1 match this value?

[jrotaetxe]

Hi, Steve.

If you do not mind, try to make the track from the pad to L1 longer (3 or 4 "S" turns), to have "metal radiating" and make the antenna longer. This will increase L1 a little but I am not concerned. The whole thing has its tolerances.

You rock, sir

Regards Jon