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The connector on the left is the DC power jack. The blown FP6291 has been removed, it goes on the SOIC-6 footprint near the top of the photo. This is the one and only PCB. On the back are two 2-wire connectors, one goes to the motor, the other to the battery.
This is a hand-held massager...
Hello,
Part 2 of my repair adventure. I'm trying to fix a PCB that received 12VDC instead of 5VDC. One part was physically blown and thanks to help on this forum I identified the part (Feeling FP6291 boost converter) and a place to buy a replacement. After removing the remains of the blow...
That looks absolutely correct, thanks! The bias resistors used in the circuit (30K and 390K) limit the output to 8.4V, which would make sense for the 7.4V motor and battery; and the circuit layout matches the typical-use.
Now I just need to find a few in stock somewhere, or an equivalent part.
I'm trying to repair a circuit board with a blown AL516 (SOT-23-6 package). I cannot find any references to this part via Internet searching, other than a seemingly similar part (AL815) on Alibaba.
I suspect this is a current-mode DC-DC booster IC based on the circuit, which drives a 7.4VDC...
I have a circuit that drives a VGA monitor using a simple 4-bit (per color) resistor DAC. This works well, colors look great, image is stable, etc. However, I also see circuits in datasheets (like the typical use schematic from AD725) or on other boards that use buffer ICs or discrete...
Thanks. I was trying to keep it as short as possible and not pull in unnecessary details. I was worried it was getting too long.
Classic home computers from the early to mid 80's mostly. They are old, but I'm always surprised at how much what we consider "modern technology" they have in...
Hello,
I have a circuit board that plugs into an existing computer system so the input is 5VDC (4.8 to 5.25 is about the range). My board carries an FPGA and I need 1.2VDC, 2.5VDC, and 3.3VDC. I have two LDOs (MCP1801 and MIC5320) that provide the required voltages to the FPGA, each with a...
Like the original chip, I need the same circuit to work in all the systems where the original chip was used. I'm making a pin-compatible replacement, so different boards for different systems is not an option.
The LTspice simulation was showing the opamp working as a very nice linear unity...
Exactly. It is done too, and generates VGA just fine, but for some reason I got this idea to ALSO generate composite video like the original 9918A because it would be "easy"... oops. ;-) I found a few examples online using two digital outputs and two resistors. But it relies on fixed loads...
Nope. I'm just generating composite gray-scale video using two digital outputs and three resistors. Like I said previously, I have the composite part working as long as the load is fixed. But, the load is not fixed, it varies depending on the computer I'm putting my circuit in to, thus I went...
I didn't build it yet. ;-) I just wanted to understand what kind of loads those circuits were presenting so I could select an opamp. I'm wiring up an OPA358 now to see how it goes.
Not yet, but I'm doing that today.
All my posted images are examples of actual circuits that *follow* the one I need to design. The original 9918A's composite output pin would be connected as the input to the circuits posted. I'm reproducing the 9918A with an FPGA, so I need to drive those...
I have the values for this circuit, I guess I didn't think it would matter in determining the kind of load...
L202 22uH
L203 8.2uH
C200 82pF
C201 10uF
R200 560-ohms
Q200 2N3906
All the circuits shown above are follow-on stages from the device creating the composite video, which is originally a...
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