# Tag Info

Accepted

### DC motor pump always transports in same direction, regardless of polarity

Some quick googling reveals that this is a membrane pump. The actual pumping action is performed by a membrane that moves up and down. The direction of the motor does not change the direction of flow ...
• 5,008

### DC motor pump always transports in same direction, regardless of polarity

The motor is reversing direction. But the air flow is not set by the direction of the motor, it is set by the one-way valves in the membrane. As the motor rotates (regardless of its rotation direction)...
• 23.2k

### How can DC charge a capacitor?

The problem is sloppy terminology. You're using "DC" to mean two different things: A circuit in which none of the voltages or currents change over time. This is a mathematical ideal. A ...
• 22.2k

### Transformer with same size symbol meaning

I wouldn't count on the number of turns or apparent size of the windings on a schematic symbol as having any relation to the actual turns ratio of the real transformer. From the voltages shown, the ...
• 60.1k

### Would a solderless breadboard be able to handle 20V without short circuiting?

I've put 2000V on breadboards before, though with careful monitoring, current limiting, and avoiding nearby positions. Possible they might even handle as much between adjacent positions... at least ...
• 40.5k

### How can DC charge a capacitor?

I read that a capacitor shows infinite resistance towards DC That is the steady state behavior, as opposed to transient behavior. Is there any clear idea on how DC cannot charge a capacitor? DC can ...
• 3,294
Accepted

### Electronically activated circuit breaker

You already have a circuit breaker, right? They make various types of actuators for these. They're basically an electromagnet that moves a little lever that flips the breaker down. There are also ...
• 79.8k
Accepted

### Capacitor connected with a DC source

I wonder what would be the graph of current be? Well, you say it's a "pure capacitor connected with a pure DC source" hence, the current will be infinite amps for an infinitesimally short ...
• 465k

### Relay which opens very infrequently

You are referring to a 'safety relay' that actually consists of three relays - two to perform the dual-redundant output function and one to monitor the status of the output contacts. Should either of ...
• 18.9k

### Would a solderless breadboard be able to handle 20V without short circuiting?

The safe limits will depend upon the quality of the solderless breadboard. As an example, Multicomp specifies the voltage and current limits of their solderless breadboards as 300 V and 3 A. A safe ...
Accepted

### LTspice showing wrong voltage

A few quick points: Do use the LTspice help. If you access it using the menu, there is an option for searching and you can use "diode" or just "d" in the search, then look down ...
• 11.5k

### Would 5.5 x 2.1 mm male plug work inside a 5.5 x 2.5 mm female jack for DC power?

Not all plugs are created equal. Some plugs have full, uniform tubes that have little tolerance, and a nominal 2.5mm center pin will not fit inside one designed for a 2.1mm pin. They look like this: (...
• 212
Accepted

### YH11068A overvoltage

The main problem is with the feedback compensation. The design seems to have a very low cross-over frequency (between 10 and 20 Hz), resulting in very low phase margins, which causes instability. ...
• 211
Accepted

### Which is the best method to measure AC voltage?

The problem The task is to detect both over-voltage and under-voltage, and to signal this condition within, let's say, 2 mains cycles, about 40ms. A strategy To detect under-voltage, the easiest "...
• 39.7k

### Transformer with same size symbol meaning

Many people draw the transformer step up and step down to show the relative size of the coils. The size (on the schematic) doesn't necessarily indicate step up or step down, but the coil ratio does, ...
• 85.3k

### How can DC charge a capacitor?

DC can charge a capacitor. It cannot pass through a capacitor. Have a look at this circuit: simulate this circuit – Schematic created using CircuitLab This is the current flowing into the ...
• 72.7k

### Relay which opens very infrequently

This isn't usually how you design such applications. You'd power the motor through the NO contacts of a relay which gets turned on at power up, so that each time you power up, you get a relay toggle ...
• 21.2k

### Op-Amp Selection for Dummies

The title of the AD820 datasheet says it is "rail-to-rail", but if you look more at the front page bullet points it only says that the output swings rail to rail, and the input may be used ...
• 132k
Accepted

### I obliterated a ceramic SMD, how to find out what piece it is?

It appears to be one of the load capacitances of the crystal which appears to be "removed": That and the one to its right have the same capacitance. Carefully remove the other capacitor to ...
• 36.9k
Accepted

### Can this circuit be used for an AC-DC emergency LED lamp?

The transistor is connected such that it only conducts when the AC power is on. The lamp will never run from the battery. A capacitive dropper AC-DC power supply (like your circuit uses) is an ...
• 72.7k

### DC motor pump always transports in same direction, regardless of polarity

There's multiple misconceptions here. A pump's direction of transport doesn't necessarily have to do with the direction that the motor powering it turns; there's many counterexamples (pumps using ...
• 97.3k

### Multimeter Range and Resolution

Unfortunately, the resolution part is what confuses me. Resolution is the smallest increment that your display can indicate. In other words, if you are on the 2 mA range then the display will be like ...
• 465k

### Is this signal classified as DC or AC, and what about the impedance?

but why do I sometimes see this 0 to +V signal being called AC? Depending on the context, you may call it "AC with DC offset", or "DC with AC component" (e.g. ripple). The DC ...
• 36.9k

### LTspice showing wrong voltage

There are some LED models already in LTspice, you can try some of them. They will have different forward voltages so each one will give you a different result. When I want to use an LED with a ...
• 25.2k
Accepted

### 24 VDC system and metal ground

What you feel is static electricity that builds up on the robot body, which is insulated from earth by the wheels and tyres. It's not caused by the 24 V system so there's nothing to be gained by ...
• 23.6k

### I obliterated a ceramic SMD, how to find out what piece it is?

I am 99% sure that if you slap down the least expensive/most popular HC49/U 16MHz crystal and an appropriate size NP0 22pF capacitor it will work fine. There is nothing that requires extreme precision ...
• 409k

### Capacitor connected with a DC source

It is possible to get an idea of the response you requested, through the behavior of the current in an RC circuit where the resistor gradually decreases in value, approaching to zero (\\$... < R3 &...
• 3,365
Accepted

### Questions About My Perpetual Motion Idea

The alternator gets harder to spin the more load there is on it (on top of the inevitable friction losses even if there is no load). Two alternators mean twice the mechanical load on the motor. It’s ...
• 409k