Antenna question

That was me. The scope is perfect for stuff like my current project. It's all at audio frequencies, which the scope handles easily. I can look at the waveforms at all the opamp inputs and outputs and see what's really gning on. My analog multimeter can give me equivalent information about the charge on a capacitor, but not the square wave stuff.

There has been some discussion about battery operation on the JYETech forum, and some design guides for that. Of course you can use a 9V battery, but at 120 ma that won't last long. I believe someone posted an 18650 lithium design.

Reply to
Peabody
Loading thread data ...

I'd suggest that anyone interested in one of these read up on the JYETech website about the latest board versions and latest firmware. I don't know if there's a way to find out from Banggood whether they are selling the latest versions now, but someone on the JYETech forum may know.

The firmware updates can be flashed later, but there's no program to update the board versions if yours is an older one.

Reply to
Peabody

Not sure what you mean about an attached scope. The display works pretty well.

The latest rumor is that they are working on a two-channel version, which is something I've really missed. I know the school-approved solution is to follow Dave Jones' advice and find a used analog scope for $50-100. I think that's probably right. Still, it's nice to have something I can put in my pocket and take to an OSH meetup. And I don't do all that much microwave stuff. :-)

Reply to
Peabody

It seems nobody likes my design. And no, I don't want this project to be another career. I guess the bottom line is that the squelching function based on channel and subcode appears to work extremely well in these radios. I had one of them on all day today, and didn't experience a single audio burst. So I'm going to rely on that to protect against any false input. As far as I've been able to determine, my design already works quite well. I think the risk of false triggering leading to someone gaining entry is very low.

And the circuit isn't exactly complicated:

formatting link

Reply to
Peabody

You didn't post a picture of the receiver board. Does it have a similar transistor circuit for the receiver and a chip for the decoder? Or did you mean the "transmitter" board? The antenna in your photo protrudes from the case and is extendable. I was surprised to see that on some remotes. In fact, some remotes in a brown case with a sliding cover and extendable antenna look exactly like others which have no protruding antenna and are waterproof, but in different colors. Before I noticed the antenna protruding I thought the brown ones might also be waterproof, lol.

BTW, did you notice your transmitter has two "S2" switches and no "S3"? Also note the antenna is secured by just one solder joint.

Yeah, detecting energy without good filtering is a great way to lose the signal in a sea of noise.

Not sure why they need to be unsoldered. They don't get pulled out of the holes. The jumper is just a solder bridge.

They used an 18 pin package. You'd think they could make it a 20 pin chip with a select instead of selling multiple chip versions.

Yep. I understand that has been done many times.

--
Rick C 

Viewed the eclipse at Wintercrest Farms, 
 Click to see the full signature
Reply to
rickman

The trace antenna I was referring to was on the reveiver board:

formatting link

On the new one that arrived today, there is no such trace antenna on the receiver. But both versions of the transmitter use the telescoping antenna.

Reply to
Peabody

Forgot to answer this part.

Yes, the receivers have two transistors, the decoder chip, and an LM386 audio amplifier (not sure what this is used for).

Reply to
Peabody

The display is tiny. I don't want to squint at displays. I have a 17" display on my laptop which a scope head can be "attached" to.

Analog scopes are fine if you have space for the mass and bulk. I remember a guy I met who salvaged Tek tube scopes and got them working well. They were ok scopes. Just as semiconductors made them totally obsolete because of their size, weight and limited capabilities, digital scopes have made analog scopes boat anchors.

Pico makes some good attached scopes. I've never understood why removing the font panel and display makes a scope more expensive though.

--
Rick C 

Viewed the eclipse at Wintercrest Farms, 
 Click to see the full signature
Reply to
rickman

Attached to a PC, so he can see it on a bigger screen. But I found that little thing to be perfectly readable even without my reading glasses.

I have a couple of other scopes that are better than Dave's $50 suggestions, but when I had to fix something out in the field and 200kHz was plenty, this was just perfect and well worth 20 bucks. Even if I never need it again. I could have used a scope attached to my laptop but I don't like holding my laptop when I'm on a ladder.

I'm not concerned about updates for such a cheap thing. It doesn't seem to have bugs, so what are they improving?

Reply to
Tom Del Rosso

I'm getting failures on your image links, "502 Bad Gateway", "504 Gateway Time-out". Any ideas?

--
Rick C 

Viewed the eclipse at Wintercrest Farms, 
 Click to see the full signature
Reply to
rickman

On a sunny day (Sun, 15 Oct 2017 01:14:20 -0400) it happened rickman wrote in :

I still only have an analog scope.. >20 MHz its over.. Apart from my own small digital single chipper that CAN output ASCII art to a PC and had FT too, full serial port control..:

formatting link
formatting link

I have no space problem with the analog, it stands on the ground. It does not lie like digital ones do...

I still do GHz work, RT-SDR spectrum analyzer, runs on PC or Raspberry, added a mixer for even higher frequencies:

formatting link

I could buy a 1 GHz sampling scope no problem, but why?

I'd rather buy an old 300 MHz bandwidth Tek. I did build a 300 MHz wide analog one in the seventies with an Russian CRT and used that BFY90 circuit diagram somebody in Tek was kind enough to publish in some magazine at that time (I personally thanked him)... For a lab what difference does the size make??? What makes a difference is that is does not lie. Digital Scopes are easy with todays ultra fast ADCs and memory, * it is just a matter of time before the Chinese come with a 1G sampler on ebay for Pico makes some good attached scopes. I've never understood why removing

Rarely need a 'panel' scope, but you can use my scope_pic for that I am sure.

Down-conversion works great too..

Reply to
Jan Panteltje

I haven't done any of the updates either, but mainly just waiting for a final version if there is one. And as you say, it works fine for me now.

They've added trigger holdoff and some other things. Here's the change history for the firmware versions:

formatting link

But you might also want to go to the main DSO150 page and download the latest manual. That will give you the current feature set. They are pretty good about documenting all this stuff as it changes.

Reply to
Peabody

I think they were having problems last night. All the pictures work fine for me this morning. Give it another try.

Reply to
Peabody

If I were to build one of these for 315 MHz, what would the measurements be? Would everything, including the number of turns, just be proportionately larger (per the wavelengths)? Or something else?

Reply to
Peabody

Yes, it is working now, but you've shown this image of the first receiver you... well, received. What does the second receiver have for an antenna. I scanned previous posts and didn't see where you described it. Is the receiver just a board, or is it in a case too?

--
Rick C 

Viewed the eclipse at Wintercrest Farms, 
 Click to see the full signature
Reply to
rickman

That is my understanding. There may be some small effect from the insulation on the wire, but that can likely be ignored.

--
Rick C 

Viewed the eclipse at Wintercrest Farms, 
 Click to see the full signature
Reply to
rickman

It's just a board. No case. Here's the picture:

formatting link

As you can see, it does not have the trace antenna that the old one had. Despite that, it does work with the new transmitter out to at least 35 feet. I'll test further outside after dark.

So here's some news. You'll recall that I thought the old transmitter, despite being sold as 315 MHz, was actually 433 MHz. That's because Y1 is marked "R433". And I raised the possibility that the old set didn't work because the transmitter was 433 and the receiver was 315.

The new transmitter has Y1 marked R315, and its telescoping antenna is significantly longer than the old one. So I think it's definitely 315. But the old receiver DOES work with the new transmitter. So I think I was right about the mismatch being the problem.

But the old receiver doesn't work nearly as well as the new one, even with no antenna at all on the new one. More than a few feet away, the relay it's triggering oscillates on and off. The new one stays on solid out to 35 feet at least.

Do you suppose the antenna on the new receiver is that three-turn coil over on the left? I thought that was an impedance matching component, but maybe it's effectively the antenna. It's hard to see what else would be performing that function.

So far the new set seems to be working well, but it's still a long way from working in the brick office building. But it would be really neat if it did.

By the way, the VT output of the receiver goes high when ANY transmitter button is pushed. That wasn't explained anywhere.

Here's the new one I bought:

formatting link

Even came with a battery. :-)

Reply to
Peabody

The old board must have been 2.4 GHz. That would have been the right antenna for that frequency. I guess you aren't using the receiver, but it needs an antenna attached.

Yeah, likely. To be sure you'd need to test the transmitter with a 433 MHz receiver. I guess even with the lame antenna it would work ok. That is what I was talking about the "design" effort that goes into these things.

Maybe it's not 315 MHz and is just working because of the field strength at close range. It's a very simple energy detector, not much selectivity.

The coil will radiate some of course, but it is not intended to be the antenna I am sure. 35 feet is not normally enough to work from a car through a garage door, etc.

When you say "set", you want to use it with an existing receiver, not the receiver you bought, right?

Yes, that is the "enable" to look at the other outputs. No, none of this is explained for squat anywhere other than blogs of those who have bought them. If any one of the vendors would spend the time to actually translate the directions they would sell a lot more, but then all the other vendors would copy their sales page, right?

I guess that is what you get for your extra $2. I see you bought in the US. From China these are $2.

--
Rick C 

Viewed the eclipse at Wintercrest Farms, 
 Click to see the full signature
Reply to
rickman

In theory, yes, but the two receiver boards are very similar in design, and I've only seen this board offered online in

433 and 315 versions. And, it didn't work with the 433 transmitter, no matter how close it was held. So I think both receivers are 315.

No. "Set" refers to a transmitter/receiver pair. I have two sets now, the original one (433 & 315) that didn't work at all, and the new pair that I just found works out to 50 feet, and not a step more, with no antenna. There was no existing receiver. I'll only be using the new stuff from here on out, because that's what works. Tomorrow I'll try adding an antenna and see what difference it makes.

The other question is whether I should replace the telescoping antenna in the transmitter with 1/4 lamdba wire. The existing antenna, including the portion inside the brown case, is a hair over 4 inches.

I ordered it Monday and received it Saturday. Worth the $2, particularly since I'm trying to be ready for the OSH meeting on Wednesday. I would like to be able to at least test the reach of the remote and the walkie talkies down to the building lobby at that meeting. Then if at least one of them works, we can start figuring out how to trigger a door unlock.

Reply to
Peabody

My crystal ball predicted 135 ft reliable range. That's under ideal conditions, through 2 brick walls, and with minimal antennas (-2dBi gain): If you have the opportunity, run a range test and see what happens.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
 Click to see the full signature
Reply to
Jeff Liebermann

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.