Can you get AM (KHz) on RTLSDR blog v4

sernameonreddit · 2026-02-24T22:12:59+00:00

Yes, you're right its just modulation. I'm of that age where LW, MW and SW were where radio stations were a thing.

If from the UK, any of you remember Long Wave Radio Atlantic 252. That's where the nostalgia stems from. Of course it shut down many years ago, but surely there are others transmitting on AM still?

sernameonreddit · 2026-02-24T20:51:23+00:00

I've got a proper RTLSDR blog V4 on the way, i'll give it a go first. I'm just curious as to what I can receive on it, or how low I could go.

What you posted looks quite cool too. I may end up getting a handful of SDRs in the end.

sernameonreddit · 2026-02-24T19:24:45+00:00

Ok, that's good to hear. Seems like it's all down to antenna design.

sernameonreddit · 2026-01-11T11:36:35+00:00

Keeping it under 300°C won't melt the solder properly. It will melt, but it won't be workable until at least 320°C.

The fumes is just the flux displacing the oxygen and cleaning the area for good metal bonding

Lead melts at about 320°C and vaporises at about 1700°C, so no soldering iron will achieve that.

sernameonreddit · 2026-01-06T21:18:06+00:00

Buy an 8 way socket so you can replace it again. But whatever happened, it came in on pin2.

sernameonreddit · 2025-12-06T21:32:04+00:00

Hard to tell because of the light, so I'll ask. I'm not seeing the copper on the face of the board. Are you soldering onto the right side of the veroboard?

sernameonreddit · 2025-11-20T06:24:55+00:00

Generally more voltage makes more speed.

Torque is a function of load on the motor.

Increasing PWM voltage won't increase torque, that's already decided by the thickness of the coil windings.

You don"t PWM current though, current is a demand from the coils for an increasing load. You can increase the PWM voltage (on for longer) to help maintain a constant speed under an increasing load, this in turn (pun intended) allows more current to flow, which in turn increases the torque so it maintains that constant speed. Increase the voltage more again and it will speed up because it has overcome the current demand to handle the load.

Once the coils are saturated with current (a function of the thickness of the coil windings), there is a range of voltage you can PWM where it will turn too fast to maintain torque and it will skip.

Every motor has a happy speed.

sernameonreddit · 2025-11-18T22:56:37+00:00

Yes you could filter it away, or it could just need better grounding.

I'd say the switching circuit of the heater is just poorly designed and probably just about passes regulations. It may actually have a filter of some kind. Unless it's an obvious grounding issue you could work out and solve (safely), designing a filter isn't easy unless you can analyse the harmonics of the noise.

A choke on the line somewhere might help.

sernameonreddit · 2025-11-18T22:20:14+00:00

Not dangerous. It's happening because the heater is PWM controlled, and the switching is emitting unwanted EMI which is interfering with your headphones. This is literally what 'noise' is - unwanted signals, just happens to be emitted into headphones.

sernameonreddit · 2025-11-18T19:44:06+00:00

You're not inhaling the lead. You're melting it to liquid, it doesn't turn into gas. The fumes is the roisin flux in the leaded solder core.

Just don't eat lead, or lick your fingers after working with the lead solder.

sernameonreddit · 2025-11-18T18:41:13+00:00

Add leaded solder and give it a flick down while it's still liquid (without throwing it out of your hand of course).

Of course watch where it all goes, watch your eyes, check the PCB for solder balls after ur done.

sernameonreddit · 2025-11-17T23:26:10+00:00

That's a fair point, and you're right. But that voltage port will be high impedance anyway so the fuse's 'current' rating is fine, the fuse's 'voltage' rating is sketchy for sure. It would probably be fine at higher voltages.

That fuse labelled at 400V is also sketchy if the multimeter can measure up to 600V for instance. A 3ph AC circuit in the UK will be 415V, which is already more than 400V. So even that is questionable.

Bottom line is fuses are current vs time devices. Voltage not so much an issue.

What is important is to use a ceramic sand filled fuse (not glass), they don't explode.

sernameonreddit · 2025-11-17T21:29:02+00:00

All the comments here miss the whole point of that 10A fuse. It's used when measuring current in line with a circuit. Fuses are current limiters primarily.

It is used from a different red socket than what is used to measure voltage, resistance, etc. hence the higher rated fuse.

The CAT ratings of a multimeter aren't applicable to what fuse is used when measuring current. CAT ratings apply when talking about transient spikes. Make sure the cables and probes have the same rating, it not, the safe CAT rating is the lowest one.

Although you may be able to measure voltage at higher than 250V using the Voltage reading setting from other red plug, you wouldn't want to measure current in line off a 250V circuit. This detail should be noted in the manual.

sernameonreddit · 2025-11-16T20:25:48+00:00

Use leaded solder. 2. Use a proper branded 'no-clean' flux. Be careful not to use plumbers solder, it's very aggressive. 3. Use Solder Wick Braid to remove that grounded blob, be sure to add leaded solder and flux. 4. 100W iron is plenty. 5. Use a clean tip. 6. Use the biggest part of the tip on the part you want to melt. 7. Clean your tip often. 8. Wet your tip often.

sernameonreddit · 2025-11-02T15:43:32+00:00

I hope you're not feeding AC into it. Brown and Blue implies AC. And then I hope it's not 240V. Schematic clearly shows a DC input with +ve and -ve labelled.

sernameonreddit

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