If the difference between both inputs is not a least 50 mV the output
remain at about 1.5 or 2V instead of beeing close to V+ or ground. What
am I doing wrong?
If the difference between both inputs is not a least 50 mV the output remain at about 1.5 or 2V instead of beeing close to V+ or ground. What am I doing wrong?
If the difference between both inputs is not a least 50 mV the output
remain at about 1.5 or 2V instead of beeing close to V+ or ground. What
am I doing wrong?
If the difference between both inputs is not a least 50 mV the output remain at about 1.5 or 2V instead of beeing close to V+ or ground. What am I doing wrong?
Jean-Pierre Coulon <coulon@cacas.pam.oca.eu> wrote:
If the difference between both inputs is not a least 50 mV the output remain >> at about 1.5 or 2V instead of beeing close to V+ or ground. What am I doing >> wrong?
If the strobe pins are high, the output will be undefined.
On 25/09/2024 11:16 pm, Jean-Pierre Coulon wrote:
If the difference between both inputs is not a least 50 mV the output
remain at about 1.5 or 2V instead of beeing close to V+ or ground. What am >> I doing wrong?
Getting it to oscillate faster than your oscilloscope can follow?
On Thu, 26 Sep 2024, Bill Sloman wrote:
On 25/09/2024 11:16 pm, Jean-Pierre Coulon wrote:
If the difference between both inputs is not a least 50 mV the output
remain at about 1.5 or 2V instead of beeing close to V+ or ground.
What am I doing wrong?
Getting it to oscillate faster than your oscilloscope can follow?
Yes this was an oscillation. A bit fast for my scope but visible.
I worked around with a 10 mV hysteresis but it is unpleasant because I
want to detect when an about 20 mV high signal goes to zero. It
oscillates with a smaller hysteresis.
On 9/25/24 19:19, Liz Tuddenham wrote:
Jean-Pierre Coulon <coulon@cacas.pam.oca.eu> wrote:
If the difference between both inputs is not a least 50 mV the output
remain at about 1.5 or 2V instead of beeing close to V+ or ground. What
am I doing wrong?
If the strobe pins are high, the output will be undefined.
That's not so. The NE521 has no latch of flipflop. What they call
strobes are actually inputs to NAND gates. If any of the strobes
are low, the associated output(s) will be forced high.
The output is a traditional Schottky TTL gate. If the OP sees
something in between a definite high or low, it's probably
oscillating. That could be because one or both of the comparator
inputs are driven from a too-high impedance, or it could be
feedback due to poor layout, or it could be poor or missing
power supply decoupling, or something else yet.
In summary, let's wait until he shows us what he did.
Jeroen Belleman
P.S. Half of the equivalent schematic in the datasheet is
nonsense.
"offset" has a particular meaning for its designers. Tha datasheet says: output undefined if abs(Va_Vb) < offset. Forget what you know about the offset of an opamp! One could expect better from a bipolar differential pair :-)
"offset" has a particular meaning for its designers. Tha datasheet says: output undefined if abs(Va_Vb) < offset. Forget what you know about the offset of an opamp! One could expect better from a bipolar differential
pair :-)
"offset" has a particular meaning for its designers. Tha datasheet says: output undefined if abs(Va_Vb) < offset. Forget what you know about the offset of an opamp! One could expect better from a bipolar differential
pair :-)
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